November 2024 - Linux-kselftest-mirror

[PATCH net-next v1 0/7] devmem TCP fixes

by Mina Almasry

A few unrelated devmem TCP fixes bundled in a series for some convenience (if that's ok). Patch 1-2: fix naming and provide page_pool_alloc_netmem for fragged netmem. Patch 3-4: fix issues with dma-buf dma addresses being potentially passed to dma_sync_for_* helpers. Patch 5-6: fix syzbot SO_DEVMEM_DONTNEED issue and add test for this case. Mina Almasry (6): net: page_pool: rename page_pool_alloc_netmem to *_netmems net: page_pool: create page_pool_alloc_netmem page_pool: disable sync for cpu for dmabuf memory provider netmem: add netmem_prefetch net: fix SO_DEVMEM_DONTNEED looping too long ncdevmem: add test for too many token_count Samiullah Khawaja (1): page_pool: Set `dma_sync` to false for devmem memory provider include/net/netmem.h | 7 ++++ include/net/page_pool/helpers.h | 50 ++++++++++++++++++-------- include/net/page_pool/types.h | 2 +- net/core/devmem.c | 9 +++-- net/core/page_pool.c | 11 +++--- net/core/sock.c | 46 ++++++++++++++---------- tools/testing/selftests/net/ncdevmem.c | 11 ++++++ 7 files changed, 93 insertions(+), 43 deletions(-) -- 2.47.0.163.g1226f6d8fa-goog

11 months, 3 weeks

3
12
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[PATCH v5 0/2] selftests/resctrl: SNC kernel support discovery

by Maciej Wieczor-Retman

Changes v5: - Tests are skipped if snc_unreliable was set. - Moved resctrlfs.c changes from patch 2/2 to 1/2. - Removed CAT changes since it's not impacted by SNC in the selftest. - Updated various comments. - Fixed a bunch of minor issues pointed out in the review. Changes v4: - Printing SNC warnings at the start of every test. - Printing SNC warnings at the end of every relevant test. - Remove global snc_mode variable, consolidate snc detection functions into one. - Correct minor mistakes. Changes v3: - Reworked patch 2. - Changed minor things in patch 1 like function name and made corrections to the patch message. Changes v2: - Removed patches 2 and 3 since now this part will be supported by the kernel. Sub-Numa Clustering (SNC) allows splitting CPU cores, caches and memory into multiple NUMA nodes. When enabled, NUMA-aware applications can achieve better performance on bigger server platforms. SNC support in the kernel was merged into x86/cache [1]. With SNC enabled and kernel support in place all the tests will function normally (aside from effective cache size). There might be a problem when SNC is enabled but the system is still using an older kernel version without SNC support. Currently the only message displayed in that situation is a guess that SNC might be enabled and is causing issues. That message also is displayed whenever the test fails on an Intel platform. Add a mechanism to discover kernel support for SNC which will add more meaning and certainty to the error message. Add runtime SNC mode detection and verify how reliable that information is. Series was tested on Ice Lake server platforms with SNC disabled, SNC-2 and SNC-4. The tests were also ran with and without kernel support for SNC. Series applies cleanly on kselftest/next. [1] https://lore.kernel.org/all/20240628215619.76401-1-tony.luck@intel.com/ Previous versions of this series: [v1] https://lore.kernel.org/all/cover.1709721159.git.maciej.wieczor-retman@inte… [v2] https://lore.kernel.org/all/cover.1715769576.git.maciej.wieczor-retman@inte… [v3] https://lore.kernel.org/all/cover.1719842207.git.maciej.wieczor-retman@inte… [v4] https://lore.kernel.org/all/cover.1720774981.git.maciej.wieczor-retman@inte… Maciej Wieczor-Retman (2): selftests/resctrl: Adjust effective L3 cache size with SNC enabled selftests/resctrl: Adjust SNC support messages tools/testing/selftests/resctrl/cmt_test.c | 8 +- tools/testing/selftests/resctrl/mba_test.c | 8 +- tools/testing/selftests/resctrl/mbm_test.c | 10 +- tools/testing/selftests/resctrl/resctrl.h | 7 + .../testing/selftests/resctrl/resctrl_tests.c | 8 +- tools/testing/selftests/resctrl/resctrlfs.c | 132 ++++++++++++++++++ 6 files changed, 166 insertions(+), 7 deletions(-) -- 2.46.2

11 months, 3 weeks

2
5
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[PATCH net-next v6 0/7] Suspend IRQs during application busy periods

by Joe Damato

Greetings: Welcome to v6, see changelog below. This revision includes only documentation changes: patch 7 has been updated with Bagas' suggestions and the htmldoc looks better as a result. In addition, this cover letter has been updated with a full re-run of the test data. We've included a new test case highlighting a case Sridhar asked about in our v3. See below. This series introduces a new mechanism, IRQ suspension, which allows network applications using epoll to mask IRQs during periods of high traffic while also reducing tail latency (compared to existing mechanisms, see below) during periods of low traffic. In doing so, this balances CPU consumption with network processing efficiency. Martin Karsten (CC'd) and I have been collaborating on this series for several months and have appreciated the feedback from the community on our RFC [1]. We've updated the cover letter and kernel documentation in an attempt to more clearly explain how this mechanism works, how applications can use it, and how it compares to existing mechanisms in the kernel. We've added an additional test case, 'fullbusy', achieved by modifying libevent for comparison. See below for a detailed description, link to the patch, and test results. I briefly mentioned this idea at netdev conf 2024 (for those who were there) and Martin described this idea in an earlier paper presented at Sigmetrics 2024 [2]. ~ The short explanation (TL;DR) We propose adding a new napi config parameter: irq_suspend_timeout to help balance CPU usage and network processing efficiency when using IRQ deferral and napi busy poll. If this parameter is set to a non-zero value *and* a user application has enabled preferred busy poll on a busy poll context (via the EPIOCSPARAMS ioctl introduced in commit 18e2bf0edf4d ("eventpoll: Add epoll ioctl for epoll_params")), then application calls to epoll_wait for that context will cause device IRQs and softirq processing to be suspended as long as epoll_wait successfully retrieves data from the NAPI. Each time data is retrieved, the irq_suspend_timeout is deferred. If/when network traffic subsides and epoll_wait returns no data, IRQ suspension is immediately reverted back to the existing napi_defer_hard_irqs and gro_flush_timeout mechanism which was introduced in commit 6f8b12d661d0 ("net: napi: add hard irqs deferral feature")). The irq_suspend_timeout serves as a safety mechanism. If userland takes a long time processing data, irq_suspend_timeout will fire and restart normal NAPI processing. For a more in depth explanation, please continue reading. ~ Comparison with existing mechanisms Interrupt mitigation can be accomplished in napi software, by setting napi_defer_hard_irqs and gro_flush_timeout, or via interrupt coalescing in the NIC. This can be quite efficient, but in both cases, a fixed timeout (or packet count) needs to be configured. However, a fixed timeout cannot effectively support both low- and high-load situations: At low load, an application typically processes a few requests and then waits to receive more input data. In this scenario, a large timeout will cause unnecessary latency. At high load, an application typically processes many requests before being ready to receive more input data. In this case, a small timeout will likely fire prematurely and trigger irq/softirq processing, which interferes with the application's execution. This causes overhead, most likely due to cache contention. While NICs attempt to provide adaptive interrupt coalescing schemes, these cannot properly take into account application-level processing. An alternative packet delivery mechanism is busy-polling, which results in perfect alignment of application processing and network polling. It delivers optimal performance (throughput and latency), but results in 100% cpu utilization and is thus inefficient for below-capacity workloads. We propose to add a new packet delivery mode that properly alternates between busy polling and interrupt-based delivery depending on busy and idle periods of the application. During a busy period, the system operates in busy-polling mode, which avoids interference. During an idle period, the system falls back to interrupt deferral, but with a small timeout to avoid excessive latencies. This delivery mode can also be viewed as an extension of basic interrupt deferral, but alternating between a small and a very large timeout. This delivery mode is efficient, because it avoids softirq execution interfering with application processing during busy periods. It can be used with blocking epoll_wait to conserve cpu cycles during idle periods. The effect of alternating between busy and idle periods is that performance (throughput and latency) is very close to full busy polling, while cpu utilization is lower and very close to interrupt mitigation. ~ Usage details IRQ suspension is introduced via a per-NAPI configuration parameter that controls the maximum time that IRQs can be suspended. Here's how it is intended to work: - The user application (or system administrator) uses the netdev-genl netlink interface to set the pre-existing napi_defer_hard_irqs and gro_flush_timeout NAPI config parameters to enable IRQ deferral. - The user application (or system administrator) sets the proposed irq_suspend_timeout parameter via the netdev-genl netlink interface to a larger value than gro_flush_timeout to enable IRQ suspension. - The user application issues the existing epoll ioctl to set the prefer_busy_poll flag on the epoll context. - The user application then calls epoll_wait to busy poll for network events, as it normally would. - If epoll_wait returns events to userland, IRQs are suspended for the duration of irq_suspend_timeout. - If epoll_wait finds no events and the thread is about to go to sleep, IRQ handling using napi_defer_hard_irqs and gro_flush_timeout is resumed. As long as epoll_wait is retrieving events, IRQs (and softirq processing) for the NAPI being polled remain disabled. When network traffic reduces, eventually a busy poll loop in the kernel will retrieve no data. When this occurs, regular IRQ deferral using gro_flush_timeout for the polled NAPI is re-enabled. Unless IRQ suspension is continued by subsequent calls to epoll_wait, it automatically times out after the irq_suspend_timeout timer expires. Regular deferral is also immediately re-enabled when the epoll context is destroyed. ~ Usage scenario The target scenario for IRQ suspension as packet delivery mode is a system that runs a dominant application with substantial network I/O. The target application can be configured to receive input data up to a certain batch size (via epoll_wait maxevents parameter) and this batch size determines the worst-case latency that application requests might experience. Because packet delivery is suspended during the target application's processing, the batch size also determines the worst-case latency of concurrent applications using the same RX queue(s). gro_flush_timeout should be set as small as possible, but large enough to make sure that a single request is likely not being interfered with. irq_suspend_timeout is largely a safety mechanism against misbehaving applications. It should be set large enough to cover the processing of an entire application batch, i.e., the factor between gro_flush_timeout and irq_suspend_timeout should roughly correspond to the maximum batch size that the target application would process in one go. ~ Design rationale The implementation of the IRQ suspension mechanism very nicely dovetails with the existing mechanism for IRQ deferral when preferred busy poll is enabled (introduced in commit 7fd3253a7de6 ("net: Introduce preferred busy-polling"), see that commit message for more details). While it would be possible to inject the suspend timeout via the existing epoll ioctl, it is more natural to avoid this path for one main reason: An epoll context is linked to NAPI IDs as file descriptors are added; this means any epoll context might suddenly be associated with a different net_device if the application were to replace all existing fds with fds from a different device. In this case, the scope of the suspend timeout becomes unclear and many edge cases for both the user application and the kernel are introduced Only a single iteration through napi busy polling is needed for this mechanism to work effectively. Since an important objective for this mechanism is preserving cpu cycles, exactly one iteration of the napi busy loop is invoked when busy_poll_usecs is set to 0. ~ Important call out in the implementation - Enabling per epoll-context preferred busy poll will now effectively lead to a nonblocking iteration through napi_busy_loop, even when busy_poll_usecs is 0. See patch 4. ~ Benchmark configs & descriptions The changes were benchmarked with memcached [3] using the benchmarking tool mutilate [4]. To facilitate benchmarking, a small patch [5] was applied to memcached 1.6.29 to allow setting per-epoll context preferred busy poll and other settings via environment variables. Another small patch [6] was applied to libevent to enable full busy-polling. Multiple scenarios were benchmarked as described below and the scripts used for producing these results can be found on github [7] (note: all scenarios use NAPI-based traffic splitting via SO_INCOMING_ID by passing -N to memcached): - base: - no other options enabled - deferX: - set defer_hard_irqs to 100 - set gro_flush_timeout to X,000 - napibusy: - set defer_hard_irqs to 100 - set gro_flush_timeout to 200,000 - enable busy poll via the existing ioctl (busy_poll_usecs = 64, busy_poll_budget = 64, prefer_busy_poll = true) - fullbusy: - set defer_hard_irqs to 100 - set gro_flush_timeout to 5,000,000 - enable busy poll via the existing ioctl (busy_poll_usecs = 1000, busy_poll_budget = 64, prefer_busy_poll = true) - change memcached's nonblocking epoll_wait invocation (via libevent) to using a 1 ms timeout - suspend0: - set defer_hard_irqs to 0 - set gro_flush_timeout to 0 - set irq_suspend_timeout to 20,000,000 - enable busy poll via the existing ioctl (busy_poll_usecs = 0, busy_poll_budget = 64, prefer_busy_poll = true) - suspendX: - set defer_hard_irqs to 100 - set gro_flush_timeout to X,000 - set irq_suspend_timeout to 20,000,000 - enable busy poll via the existing ioctl (busy_poll_usecs = 0, busy_poll_budget = 64, prefer_busy_poll = true) ~ Benchmark results Tested on: Single socket AMD EPYC 7662 64-Core Processor Hyperthreading disabled 4 NUMA Zones (NPS=4) 16 CPUs per NUMA zone (64 cores total) 2 x Dual port 100gbps Mellanox Technologies ConnectX-5 Ex EN NIC The test machine is configured such that a single interface has 8 RX queues. The queues' IRQs and memcached are pinned to CPUs that are NUMA-local to the interface which is under test. The NIC's interrupt coalescing configuration is left at boot-time defaults. Results: Results are shown below. The mechanism added by this series is represented by the 'suspend' cases. Data presented shows a summary over at least 15 runs of each test case [8] using the scripts on github [7]. For latency, the median is shown. For throughput and CPU utilization, the average is shown. The results also include cycles-per-query (cpq) and instruction-per-query (ipq) metrics, following the methodology proposed in [2], to augment the CPU utilization numbers, which could be skewed due to frequency scaling. We find that this does not appear to be the case as CPU utilization and low-level metrics show similar trends. These results were captured using the scripts on github [7] to illustrate how this approach compares with other pre-existing mechanisms. This data is not to be interpreted as scientific data captured in a fully isolated lab setting, but instead as best effort, illustrative information comparing and contrasting tradeoffs. The absolute QPS results are higher than our previous submission, but the relative differences between variants are equivalent. Because the patches have been rebased on 6.12, several factors have likely influenced the overall performance. Most importantly, we had to switch to a new set of basic kernel options, which has likely altered the baseline performance. Because the overall comparison of variants still holds, we have not attempted to recreate the exact set of kernel options from the previous submission. Compare: - Throughput (MAX) and latencies of base vs suspend. - CPU usage of napibusy and fullbusy during lower load (200K, 400K for example) vs suspend. - Latency of the defer variants vs suspend as timeout and load increases. - suspend0, which sets defer_hard_irqs and gro_flush_timeout to 0, has nearly the same performance as the base case (this is FAQ item #1). The overall takeaway is that the suspend variants provide a superior combination of high throughput, low latency, and low cpu utilization compared to all other variants. Each of the suspend variants works very well, but some fine-tuning between latency and cpu utilization is still possible by tuning the small timeout (gro_flush_timeout). Note: we've reorganized the results to make comparison among testcases with the same load easier. testcase load qps avglat 95%lat 99%lat cpu cpq ipq base 200K 199954 112 237 415 26 13040 11336 defer10 200K 200002 54 123 142 28 19033 16508 defer20 200K 199985 60 130 153 26 15737 14247 defer50 200K 199968 78 142 181 23 12113 11609 defer200 200K 199997 163 252 304 18 8449 9155 fullbusy 200K 199993 46 117 132 100 43959 23320 napibusy 200K 200006 100 237 275 56 25016 24866 suspend0 200K 200012 105 249 432 29 14369 11844 suspend10 200K 200004 53 123 141 32 19432 16752 suspend20 200K 200014 58 126 151 30 16356 14670 suspend50 200K 200018 73 134 176 26 13245 12416 suspend200 200K 200027 149 250 302 20 9508 9781 testcase load qps avglat 95%lat 99%lat cpu cpq ipq base 400K 399984 139 268 715 40 9437 9299 defer10 400K 400002 59 133 165 53 14089 12908 defer20 400K 400016 66 140 171 47 12085 11682 defer50 400K 400037 87 161 198 39 9528 9879 defer200 400K 399954 181 273 329 32 7326 8438 fullbusy 400K 399951 50 123 155 100 21990 16097 napibusy 400K 399997 76 221 271 83 18260 16511 suspend0 400K 399991 125 337 768 48 11051 9629 suspend10 400K 399990 57 129 161 54 13629 12841 suspend20 400K 399922 61 135 167 49 12055 11715 suspend50 400K 400024 75 148 186 42 10049 10243 suspend200 400K 399936 154 267 325 34 7770 8677 testcase load qps avglat 95%lat 99%lat cpu cpq ipq base 600K 600064 148 265 576 61 9276 8757 defer10 600K 599985 71 147 204 76 12048 10863 defer20 600K 600024 75 151 199 66 10572 10328 defer50 600K 600054 94 172 217 55 8584 9144 defer200 600K 600030 200 299 355 45 6874 8189 fullbusy 600K 599956 55 127 176 100 14650 13968 napibusy 600K 599956 64 163 252 96 14022 14153 suspend0 600K 600029 126 306 724 70 10393 8977 suspend10 600K 599997 63 137 194 70 10991 11005 suspend20 600K 600012 67 141 194 65 10108 10359 suspend50 600K 600045 80 157 203 57 8747 9320 suspend200 600K 599940 158 277 344 48 7221 8354 testcase load qps avglat 95%lat 99%lat cpu cpq ipq base 800K 800025 179 298 555 86 9572 8297 defer10 800K 799275 224 633 1271 96 10679 8904 defer20 800K 800041 114 226 328 90 10122 8917 defer50 800K 799936 118 207 288 77 8820 8607 defer200 800K 799994 228 341 403 65 7424 8130 fullbusy 800K 799964 62 136 192 100 10992 12518 napibusy 800K 799971 65 142 216 99 10911 12529 suspend0 800K 799965 126 250 533 86 9489 8496 suspend10 800K 799995 69 145 201 83 9475 9764 suspend20 800K 799931 74 151 209 79 8976 9336 suspend50 800K 799946 87 168 224 71 7993 8794 suspend200 800K 799993 160 292 357 62 6967 8184 testcase load qps avglat 95%lat 99%lat cpu cpq ipq base 1000K 915792 3498 5740 6239 97 9388 7930 defer10 1000K 876285 3896 6095 6418 99 9960 8542 defer20 1000K 914909 3107 5771 6283 97 9407 8284 defer50 1000K 928426 2977 5591 5931 97 9214 8012 defer200 1000K 959989 3097 5306 5929 96 8816 7908 fullbusy 1000K 1000102 74 155 213 100 8796 10559 napibusy 1000K 1000006 74 154 216 100 8787 10654 suspend0 1000K 960757 2223 5715 7029 98 8964 7993 suspend10 1000K 999926 80 162 222 92 8246 8922 suspend20 1000K 1000095 85 166 226 89 7966 8719 suspend50 1000K 1000067 96 180 238 84 7476 8419 suspend200 1000K 999968 163 298 363 76 6798 8061 testcase load qps avglat 95%lat 99%lat cpu cpq ipq base MAX 1054805 4152 5298 5743 100 8332 7890 defer10 MAX 937098 4598 6010 6347 100 9378 8407 defer20 MAX 988905 4389 5637 5990 100 8886 8106 defer50 MAX 1067194 3960 5216 5544 100 8235 7911 defer200 MAX 1054967 4084 5496 5821 100 8323 7871 fullbusy MAX 1248006 3472 3918 3979 100 7050 7919 napibusy MAX 1128384 3742 7958 10753 100 7776 7872 suspend0 MAX 1034456 4242 5668 6042 100 8497 7912 suspend10 MAX 1229229 3513 3926 3986 100 7156 7937 suspend20 MAX 1226845 3514 3939 3985 100 7171 7937 suspend50 MAX 1230757 3513 3935 3983 100 7140 7935 suspend200 MAX 1230424 3503 3934 3984 100 7142 7927 ~ FAQ - Why is a new parameter needed? Does irq_suspend_timeout override gro_flush_timeout? Using the suspend mechanism causes the system to alternate between polling mode and irq-driven packet delivery. During busy periods, irq_suspend_timeout overrides gro_flush_timeout and keeps the system busy polling, but when epoll finds no events, the setting of gro_flush_timeout and napi_defer_hard_irqs determine the next step. There are essentially three possible loops for network processing and packet delivery: 1) hardirq -> softirq -> napi poll; basic interrupt delivery 2) timer -> softirq -> napi poll; deferred irq processing 3) epoll -> busy-poll -> napi poll; busy looping Loop 2 can take control from Loop 1, if gro_flush_timeout and napi_defer_hard_irqs are set. If gro_flush_timeout and napi_defer_hard_irqs are set, Loops 2 and 3 "wrestle" with each other for control. During busy periods, irq_suspend_timeout is used as timer in Loop 2, which essentially tilts this in favour of Loop 3. If gro_flush_timeout and napi_defer_hard_irqs are not set, Loop 3 cannot take control from Loop 1. Therefore, setting gro_flush_timeout and napi_defer_hard_irqs is the recommended usage, because otherwise setting irq_suspend_timeout might not have any discernible effect. This is shown in the results above: compare suspend0 with the base case. Note that the lack of napi_defer_hard_irqs and gro_flush_timeout produce similar results for both, which encourages the use of napi_defer_hard_irqs and gro_flush_timeout in addition to irq_suspend_timeout. - Can the new timeout value be threaded through the new epoll ioctl ? Only with difficulty. The epoll ioctl sets options on an epoll context and the NAPI ID associated with an epoll context can change based on what file descriptors a user app adds to the epoll context. This would introduce complexity in the API from the user perspective and also complexity in the kernel. - Can irq suspend be built by combining NIC coalescing and gro_flush_timeout ? No. The problem is that the long timeout must engage if and only if prefer-busy is active. When using NIC coalescing for the short timeout (without napi_defer_hard_irqs/gro_flush_timeout), an interrupt after an idle period will trigger softirq, which will run napi polling. At this point, prefer-busy is not active, so NIC interrupts would be re-enabled. Then it is not possible for the longer timeout to interject to switch control back to polling. In other words, only by using the software timer for the short timeout, it is possible to extend the timeout without having to reprogram the NIC timer or reach down directly and disable interrupts. Using gro_flush_timeout for the long timeout also has problems, for the same underlying reason. In the current napi implementation, gro_flush_timeout is not tied to prefer-busy. We'd either have to change that and in the process modify the existing deferral mechanism, or introduce a state variable to determine whether gro_flush_timeout is used as long timeout for irq suspend or whether it is used for its default purpose. In an earlier version, we did try something similar to the latter and made it work, but it ends up being a lot more convoluted than our current proposal. - Isn't it already possible to combine busy looping with irq deferral? Yes, in fact enabling irq deferral via napi_defer_hard_irqs and gro_flush_timeout is a precondition for prefer_busy_poll to have an effect. If the application also uses a tight busy loop with essentially nonblocking epoll_wait (accomplished with a very short timeout parameter), this is the fullbusy case shown in the results. An application using blocking epoll_wait is shown as the napibusy case in the results. It's a hybrid approach that provides limited latency benefits compared to the base case and plain irq deferral, but not as good as fullbusy or suspend. ~ Special thanks Several people were involved in earlier stages of the development of this mechanism whom we'd like to thank: - Peter Cai (CC'd), for the initial kernel patch and his contributions to the paper. - Mohammadamin Shafie (CC'd), for testing various versions of the kernel patch and providing helpful feedback. Thanks, Martin and Joe [1]: https://lore.kernel.org/netdev/20240812125717.413108-1-jdamato@fastly.com/ [2]: https://doi.org/10.1145/3626780 [3]: https://github.com/memcached/memcached/blob/master/doc/napi_ids.txt [4]: https://github.com/leverich/mutilate [5]: https://raw.githubusercontent.com/martinkarsten/irqsuspend/main/patches/mem… [6]: https://raw.githubusercontent.com/martinkarsten/irqsuspend/main/patches/lib… [7]: https://github.com/martinkarsten/irqsuspend [8]: https://github.com/martinkarsten/irqsuspend/tree/main/results v6: - Updated the cover letter with a full re-run of all test cases, including a new case suspend0, as requested by Sridhar previously. - Updated the kernel documentation in patch 7 as suggested by Bagas Sanjaya, which improved the htmldoc output. v5: https://lore.kernel.org/netdev/20241103052421.518856-1-jdamato@fastly.com/ - Adjusted patch 5 to only suspend IRQs when ep_send_events returns a positive return value. This issue was pointed out by Hillf Danton. - Updated the commit message of patch 6 which still mentioned netcat, despite the code being updated in v4 to replace it with socat and fixed misspelling of netdevsim. - Fixed a minor typo in patch 7 and removed an unnecessary paragraph. - Added Sridhar Samudrala's Reviewed-by to patch 1-5 and 7. v4: https://lore.kernel.org/netdev/20241102005214.32443-1-jdamato@fastly.com/ - Added a new FAQ item to cover letter. - Updated patch 6 to use socat instead of nc in busy_poll_test.sh and updated busy_poller.c to use netlink directly to configure napi params. - Updated the kernel documentation in patch 7 to include more details. - Dropped Stanislav's Acked-by and Bagas' Reviewed-by from patch 7 since the documentation was updated. v3: https://lore.kernel.org/netdev/20241101004846.32532-1-jdamato@fastly.com/ - Added Stanislav Fomichev's Acked-by to every patch except the newly added selftest. - Added Bagas Sanjaya's Reviewed-by to the documentation patch. - Fixed the commit message of patch 2 to remove a reference to the now non-existent sysfs setting. - Added a self test which tests both "regular" busy poll and busy poll with suspend enabled. This was added as patch 6 as requested by Paolo. netdevsim was chosen instead of veth due to netdevsim's pre-existing support for netdev-genl. See the commit message of patch 6 for more details. v2: https://lore.kernel.org/bpf/20241021015311.95468-1-jdamato@fastly.com/ - Cover letter updated, including a re-run of test data. - Patch 1 rewritten to use netdev-genl instead of sysfs. - Patch 3 updated with a comment added to napi_resume_irqs. - Patch 4 rebased to apply now that commit b9ca079dd6b0 ("eventpoll: Annotate data-race of busy_poll_usecs") has been picked up from VFS. - Patch 6 updated the kernel documentation. rfc -> v1: - Cover letter updated to include more details. - Patch 1 updated to remove the documentation added. This was moved to patch 6 with the rest of the docs (see below). - Patch 5 updated to fix an error uncovered by the kernel build robot. See patch 5's changelog for more details. - Patch 6 added which updates kernel documentation. Joe Damato (2): selftests: net: Add busy_poll_test docs: networking: Describe irq suspension Martin Karsten (5): net: Add napi_struct parameter irq_suspend_timeout net: Suspend softirq when prefer_busy_poll is set net: Add control functions for irq suspension eventpoll: Trigger napi_busy_loop, if prefer_busy_poll is set eventpoll: Control irq suspension for prefer_busy_poll Documentation/netlink/specs/netdev.yaml | 7 + Documentation/networking/napi.rst | 170 ++++++++- fs/eventpoll.c | 36 +- include/linux/netdevice.h | 2 + include/net/busy_poll.h | 3 + include/uapi/linux/netdev.h | 1 + net/core/dev.c | 58 +++- net/core/dev.h | 25 ++ net/core/netdev-genl-gen.c | 5 +- net/core/netdev-genl.c | 12 + tools/include/uapi/linux/netdev.h | 1 + tools/testing/selftests/net/.gitignore | 1 + tools/testing/selftests/net/Makefile | 3 +- tools/testing/selftests/net/busy_poll_test.sh | 164 +++++++++ tools/testing/selftests/net/busy_poller.c | 328 ++++++++++++++++++ 15 files changed, 805 insertions(+), 11 deletions(-) create mode 100755 tools/testing/selftests/net/busy_poll_test.sh create mode 100644 tools/testing/selftests/net/busy_poller.c base-commit: dbb9a7ef347828870df3e5e6ddf19469a3277fc9 -- 2.25.1

11 months, 3 weeks

2
3
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[PATCH net-next v7 00/12] selftests: ncdevmem: Add ncdevmem to ksft

by Stanislav Fomichev

The goal of the series is to simplify and make it possible to use ncdevmem in an automated way from the ksft python wrapper. ncdevmem is slowly mutated into a state where it uses stdout to print the payload and the python wrapper is added to make sure the arrived payload matches the expected one. v7: - fix validation (Mina) - add support for working with non ::ffff-prefixed addresses (Mina) v6: - fix compilation issue in 'Unify error handling' patch (Jakub) v5: - properly handle errors from inet_pton() and socket() (Paolo) - remove unneeded import from python selftest (Paolo) v4: - keep usage example with validation (Mina) - fix compilation issue in one patch (s/start_queues/start_queue/) v3: - keep and refine the comment about ncdevmem invocation (Mina) - add the comment about not enforcing exit status for ntuple reset (Mina) - make configure_headersplit more robust (Mina) - use num_queues/2 in selftest and let the users override it (Mina) - remove memory_provider.memcpy_to_device (Mina) - keep ksft as is (don't use -v validate flags): we are gonna need a --debug-disable flag to make it less chatty; otherwise it times out when sending too much data; so leaving it as a separate follow up v2: - don't remove validation (Mina) - keep 5-tuple flow steering but use it only when -c is provided (Mina) - remove separate flag for probing (Mina) - move ncdevmem under drivers/net/hw, not drivers/net (Jakub) Cc: Mina Almasry <almasrymina(a)google.com> Stanislav Fomichev (12): selftests: ncdevmem: Redirect all non-payload output to stderr selftests: ncdevmem: Separate out dmabuf provider selftests: ncdevmem: Unify error handling selftests: ncdevmem: Make client_ip optional selftests: ncdevmem: Remove default arguments selftests: ncdevmem: Switch to AF_INET6 selftests: ncdevmem: Properly reset flow steering selftests: ncdevmem: Use YNL to enable TCP header split selftests: ncdevmem: Remove hard-coded queue numbers selftests: ncdevmem: Run selftest when none of the -s or -c has been provided selftests: ncdevmem: Move ncdevmem under drivers/net/hw selftests: ncdevmem: Add automated test .../selftests/drivers/net/hw/.gitignore | 1 + .../testing/selftests/drivers/net/hw/Makefile | 9 + .../selftests/drivers/net/hw/devmem.py | 45 + .../selftests/drivers/net/hw/ncdevmem.c | 786 ++++++++++++++++++ tools/testing/selftests/net/.gitignore | 1 - tools/testing/selftests/net/Makefile | 8 - tools/testing/selftests/net/ncdevmem.c | 570 ------------- 7 files changed, 841 insertions(+), 579 deletions(-) create mode 100644 tools/testing/selftests/drivers/net/hw/.gitignore create mode 100755 tools/testing/selftests/drivers/net/hw/devmem.py create mode 100644 tools/testing/selftests/drivers/net/hw/ncdevmem.c delete mode 100644 tools/testing/selftests/net/ncdevmem.c -- 2.47.0

11 months, 3 weeks

4
30
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[PATCH v3 0/4] Add support for the Bus Lock Threshold

by Manali Shukla

Misbehaving guests can cause bus locks to degrade the performance of a system. Non-WB (write-back) and misaligned locked RMW (read-modify-write) instructions are referred to as "bus locks" and require system wide synchronization among all processors to guarantee the atomicity. The bus locks can impose notable performance penalties for all processors within the system. Support for the Bus Lock Threshold is indicated by CPUID Fn8000_000A_EDX[29] BusLockThreshold=1, the VMCB provides a Bus Lock Threshold enable bit and an unsigned 16-bit Bus Lock Threshold count. VMCB intercept bit VMCB Offset Bits Function 14h 5 Intercept bus lock operations Bus lock threshold count VMCB Offset Bits Function 120h 15:0 Bus lock counter During VMRUN, the bus lock threshold count is fetched and stored in an internal count register. Prior to executing a bus lock within the guest, the processor verifies the count in the bus lock register. If the count is greater than zero, the processor executes the bus lock, reducing the count. However, if the count is zero, the bus lock operation is not performed, and instead, a Bus Lock Threshold #VMEXIT is triggered to transfer control to the Virtual Machine Monitor (VMM). A Bus Lock Threshold #VMEXIT is reported to the VMM with VMEXIT code 0xA5h, VMEXIT_BUSLOCK. EXITINFO1 and EXITINFO2 are set to 0 on a VMEXIT_BUSLOCK. On a #VMEXIT, the processor writes the current value of the Bus Lock Threshold Counter to the VMCB. More details about the Bus Lock Threshold feature can be found in AMD APM [1]. v2 -> v3 - Drop parch to add virt tag in /proc/cpuinfo. - Incorporated Tom's review comments. v1 -> v2 - Incorporated misc review comments from Sean. - Removed bus_lock_counter module parameter. - Set the value of bus_lock_counter to zero by default and reload the value by 1 in bus lock exit handler. - Add documentation for the behavioral difference for KVM_EXIT_BUS_LOCK. - Improved selftest for buslock to work on SVM and VMX. - Rewrite the commit messages. Patches are prepared on kvm-next/next (efbc6bd090f4). Testing done: - Added a selftest for the Bus Lock Threshold functionality. - The bus lock threshold selftest has been tested on both Intel and AMD platforms. - Tested the Bus Lock Threshold functionality on SEV, SEV-ES, SEV-SNP guests. - Tested the Bus Lock Threshold functionality on nested guests. v1: https://lore.kernel.org/kvm/20240709175145.9986-4-manali.shukla@amd.com/T/ v2: https://lore.kernel.org/kvm/20241001063413.687787-4-manali.shukla@amd.com/T/ [1]: AMD64 Architecture Programmer's Manual Pub. 24593, April 2024, Vol 2, 15.14.5 Bus Lock Threshold. https://bugzilla.kernel.org/attachment.cgi?id=306250 Manali Shukla (2): x86/cpufeatures: Add CPUID feature bit for the Bus Lock Threshold KVM: X86: Add documentation about behavioral difference for KVM_EXIT_BUS_LOCK Nikunj A Dadhania (2): KVM: SVM: Enable Bus lock threshold exit KVM: selftests: Add bus lock exit test Documentation/virt/kvm/api.rst | 4 + arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/include/asm/svm.h | 5 +- arch/x86/include/uapi/asm/svm.h | 2 + arch/x86/kvm/svm/nested.c | 10 ++ arch/x86/kvm/svm/svm.c | 27 ++++ tools/testing/selftests/kvm/Makefile | 1 + .../selftests/kvm/x86_64/kvm_buslock_test.c | 130 ++++++++++++++++++ 8 files changed, 179 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/kvm/x86_64/kvm_buslock_test.c base-commit: efbc6bd090f48ccf64f7a8dd5daea775821d57ec -- 2.34.1

11 months, 3 weeks

4
13
0 0

Testing Quality Call notes - 2024-10-31

by Laura Nao

Hello, KernelCI is hosting a bi-weekly call on Thursday to discuss improvements to existing upstream tests, the development of new tests to increase kernel testing coverage, and the enablement of these tests in KernelCI. In recent months, we at Collabora have focused on various kernel areas, assessing the tests already available upstream and contributing patches to make them easily runnable in CIs. Below is a list of the tests we've been working on and their latest status updates, as discussed in the last meeting held on 2024-10-31: *Boot time test* - Sent v2: https://lore.kernel.org/all/20241018101439.20849-1-laura.nao@collabora.com/ - Changes in v2 driven by feedback received in the LPC session *ACPI probe kselftest* - RFCv2: https://lore.kernel.org/all/20240308144933.337107-1-laura.nao@collabora.com/ - Related upstream discussion on probe status tracking through printks: https://lore.kernel.org/lkml/dc7af563-530d-4e1f-bcbb-90bcfc2fe11a@stanley.m… Please reply to this thread if you'd like to join the call or discuss any of the topics further. We look forward to collaborating with the community to improve upstream tests and expand coverage to more areas of interest within the kernel. Best regards, Laura Nao

11 months, 3 weeks

1
0
0 0

[PATCH net-next v2 0/4] Introduce VLAN support in HSR

by MD Danish Anwar

This series adds VLAN support to HSR framework. This series also adds VLAN support to HSR mode of ICSSG Ethernet driver. Changes from v1 to v2: *) Added patch 4/4 to add test script related to VLAN in HSR as asked by Lukasz Majewski <lukma(a)denx.de> v1 https://lore.kernel.org/all/20241004074715.791191-1-danishanwar@ti.com/ MD Danish Anwar (1): selftests: hsr: Add test for VLAN Murali Karicheri (1): net: hsr: Add VLAN CTAG filter support Ravi Gunasekaran (1): net: ti: icssg-prueth: Add VLAN support for HSR mode WingMan Kwok (1): net: hsr: Add VLAN support drivers/net/ethernet/ti/icssg/icssg_prueth.c | 45 +++++++++++- net/hsr/hsr_device.c | 76 ++++++++++++++++++-- net/hsr/hsr_forward.c | 19 +++-- tools/testing/selftests/net/hsr/config | 1 + tools/testing/selftests/net/hsr/hsr_ping.sh | 63 +++++++++++++++- 5 files changed, 191 insertions(+), 13 deletions(-) base-commit: 1bf70e6c3a5346966c25e0a1ff492945b25d3f80 -- 2.34.1

11 months, 3 weeks

4
10
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[PATCH net v6] ipv6: Fix soft lockups in fib6_select_path under high next hop churn

by Omid Ehtemam-Haghighi

Soft lockups have been observed on a cluster of Linux-based edge routers located in a highly dynamic environment. Using the `bird` service, these routers continuously update BGP-advertised routes due to frequently changing nexthop destinations, while also managing significant IPv6 traffic. The lockups occur during the traversal of the multipath circular linked-list in the `fib6_select_path` function, particularly while iterating through the siblings in the list. The issue typically arises when the nodes of the linked list are unexpectedly deleted concurrently on a different core—indicated by their 'next' and 'previous' elements pointing back to the node itself and their reference count dropping to zero. This results in an infinite loop, leading to a soft lockup that triggers a system panic via the watchdog timer. Apply RCU primitives in the problematic code sections to resolve the issue. Where necessary, update the references to fib6_siblings to annotate or use the RCU APIs. Include a test script that reproduces the issue. The script periodically updates the routing table while generating a heavy load of outgoing IPv6 traffic through multiple iperf3 clients. It consistently induces infinite soft lockups within a couple of minutes. Kernel log: 0 [ffffbd13003e8d30] machine_kexec at ffffffff8ceaf3eb 1 [ffffbd13003e8d90] __crash_kexec at ffffffff8d0120e3 2 [ffffbd13003e8e58] panic at ffffffff8cef65d4 3 [ffffbd13003e8ed8] watchdog_timer_fn at ffffffff8d05cb03 4 [ffffbd13003e8f08] __hrtimer_run_queues at ffffffff8cfec62f 5 [ffffbd13003e8f70] hrtimer_interrupt at ffffffff8cfed756 6 [ffffbd13003e8fd0] __sysvec_apic_timer_interrupt at ffffffff8cea01af 7 [ffffbd13003e8ff0] sysvec_apic_timer_interrupt at ffffffff8df1b83d -- <IRQ stack> -- 8 [ffffbd13003d3708] asm_sysvec_apic_timer_interrupt at ffffffff8e000ecb [exception RIP: fib6_select_path+299] RIP: ffffffff8ddafe7b RSP: ffffbd13003d37b8 RFLAGS: 00000287 RAX: ffff975850b43600 RBX: ffff975850b40200 RCX: 0000000000000000 RDX: 000000003fffffff RSI: 0000000051d383e4 RDI: ffff975850b43618 RBP: ffffbd13003d3800 R8: 0000000000000000 R9: ffff975850b40200 R10: 0000000000000000 R11: 0000000000000000 R12: ffffbd13003d3830 R13: ffff975850b436a8 R14: ffff975850b43600 R15: 0000000000000007 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 9 [ffffbd13003d3808] ip6_pol_route at ffffffff8ddb030c 10 [ffffbd13003d3888] ip6_pol_route_input at ffffffff8ddb068c 11 [ffffbd13003d3898] fib6_rule_lookup at ffffffff8ddf02b5 12 [ffffbd13003d3928] ip6_route_input at ffffffff8ddb0f47 13 [ffffbd13003d3a18] ip6_rcv_finish_core.constprop.0 at ffffffff8dd950d0 14 [ffffbd13003d3a30] ip6_list_rcv_finish.constprop.0 at ffffffff8dd96274 15 [ffffbd13003d3a98] ip6_sublist_rcv at ffffffff8dd96474 16 [ffffbd13003d3af8] ipv6_list_rcv at ffffffff8dd96615 17 [ffffbd13003d3b60] __netif_receive_skb_list_core at ffffffff8dc16fec 18 [ffffbd13003d3be0] netif_receive_skb_list_internal at ffffffff8dc176b3 19 [ffffbd13003d3c50] napi_gro_receive at ffffffff8dc565b9 20 [ffffbd13003d3c80] ice_receive_skb at ffffffffc087e4f5 [ice] 21 [ffffbd13003d3c90] ice_clean_rx_irq at ffffffffc0881b80 [ice] 22 [ffffbd13003d3d20] ice_napi_poll at ffffffffc088232f [ice] 23 [ffffbd13003d3d80] __napi_poll at ffffffff8dc18000 24 [ffffbd13003d3db8] net_rx_action at ffffffff8dc18581 25 [ffffbd13003d3e40] __do_softirq at ffffffff8df352e9 26 [ffffbd13003d3eb0] run_ksoftirqd at ffffffff8ceffe47 27 [ffffbd13003d3ec0] smpboot_thread_fn at ffffffff8cf36a30 28 [ffffbd13003d3ee8] kthread at ffffffff8cf2b39f 29 [ffffbd13003d3f28] ret_from_fork at ffffffff8ce5fa64 30 [ffffbd13003d3f50] ret_from_fork_asm at ffffffff8ce03cbb Fixes: 66f5d6ce53e6 ("ipv6: replace rwlock with rcu and spinlock in fib6_table") Reported-by: Adrian Oliver <kernel(a)aoliver.ca> Signed-off-by: Omid Ehtemam-Haghighi <omid.ehtemamhaghighi(a)menlosecurity.com> Cc: David S. Miller <davem(a)davemloft.net> Cc: David Ahern <dsahern(a)gmail.com> Cc: Eric Dumazet <edumazet(a)google.com> Cc: Jakub Kicinski <kuba(a)kernel.org> Cc: Paolo Abeni <pabeni(a)redhat.com> Cc: Shuah Khan <shuah(a)kernel.org> Cc: Ido Schimmel <idosch(a)idosch.org> Cc: Kuniyuki Iwashima <kuniyu(a)amazon.com> Cc: Simon Horman <horms(a)kernel.org> Cc: netdev(a)vger.kernel.org Cc: linux-kselftest(a)vger.kernel.org Cc: linux-kernel(a)vger.kernel.org --- v5 -> v6: * Adjust the comment line lengths in the test script to a maximum of 80 characters * Change memory allocation in inet6_rt_notify from gfp_any() to GFP_ATOMIC for atomic allocation in non-blocking contexts, as suggested by Ido Schimmel * NOTE: I have executed the test script on both bare-metal servers and virtualized environments such as QEMU and vng. In the case of bare-metal, it consistently triggers a soft lockup in under a minute on unpatched kernels. For the virtualized environments, an unpatched kernel compiled with the Ubuntu 24.04 configuration also triggers a soft lockup, though it takes longer; however, it did not trigger a soft lockup on kernels compiled with configurations provided in: https://github.com/linux-netdev/nipa/wiki/How-to-run-netdev-selftests-CI-st… leading to potential false negatives in the test results. I am curious if this test can be executed on a bare-metal machine within a CI system, if such a setup exists, rather than in a virtualized environment. If that’s not possible, how can I apply a different kernel configuration, such as the one used in Ubuntu 24.04, for this test? Please advise. v4 -> v5: * Addressed review comments from Paolo Abeni. * Added additional clarifying comments in the test script. * Minor cleanup performed in the test script. v3 -> v4: * Added RCU primitives to rt6_fill_node(). I found that this function is typically called either with a table lock held or within rcu_read_lock/rcu_read_unlock pairs, except in the following call chain, where the protection is unclear: rt_fill_node() fib6_info_hw_flags_set() mlxsw_sp_fib6_offload_failed_flag_set() mlxsw_sp_router_fib6_event_work() The last function is initialized as a work item in mlxsw_sp_router_fib_event() and scheduled for deferred execution. I am unsure if the execution context of this work item is protected by any table lock or rcu_read_lock/rcu_read_unlock pair, so I have added the protection. Please let me know if this is redundant. * Other review comments addressed v2 -> v3: * Removed redundant rcu_read_lock()/rcu_read_unlock() pairs * Revised the test script based on Ido Schimmel's feedback * Updated the test script to ensure compatibility with the latest iperf3 version * Fixed new warnings generated with 'C=2' in the previous version * Other review comments addressed v1 -> v2: * list_del_rcu() is applied exclusively to legacy multipath code * All occurrences of fib6_siblings have been modified to utilize RCU APIs for annotation and usage. * Additionally, a test script for reproducing the reported issue is included --- net/ipv6/ip6_fib.c | 8 +- net/ipv6/route.c | 45 ++- tools/testing/selftests/net/Makefile | 1 + .../net/ipv6_route_update_soft_lockup.sh | 262 ++++++++++++++++++ 4 files changed, 297 insertions(+), 19 deletions(-) create mode 100755 tools/testing/selftests/net/ipv6_route_update_soft_lockup.sh diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index eb111d20615c..9a1c59275a10 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -1190,8 +1190,8 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt, while (sibling) { if (sibling->fib6_metric == rt->fib6_metric && rt6_qualify_for_ecmp(sibling)) { - list_add_tail(&rt->fib6_siblings, - &sibling->fib6_siblings); + list_add_tail_rcu(&rt->fib6_siblings, + &sibling->fib6_siblings); break; } sibling = rcu_dereference_protected(sibling->fib6_next, @@ -1252,7 +1252,7 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt, fib6_siblings) sibling->fib6_nsiblings--; rt->fib6_nsiblings = 0; - list_del_init(&rt->fib6_siblings); + list_del_rcu(&rt->fib6_siblings); rt6_multipath_rebalance(next_sibling); return err; } @@ -1970,7 +1970,7 @@ static void fib6_del_route(struct fib6_table *table, struct fib6_node *fn, &rt->fib6_siblings, fib6_siblings) sibling->fib6_nsiblings--; rt->fib6_nsiblings = 0; - list_del_init(&rt->fib6_siblings); + list_del_rcu(&rt->fib6_siblings); rt6_multipath_rebalance(next_sibling); } diff --git a/net/ipv6/route.c b/net/ipv6/route.c index b4251915585f..b9b986bda943 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -413,8 +413,8 @@ void fib6_select_path(const struct net *net, struct fib6_result *res, struct flowi6 *fl6, int oif, bool have_oif_match, const struct sk_buff *skb, int strict) { - struct fib6_info *sibling, *next_sibling; struct fib6_info *match = res->f6i; + struct fib6_info *sibling; if (!match->nh && (!match->fib6_nsiblings || have_oif_match)) goto out; @@ -440,8 +440,8 @@ void fib6_select_path(const struct net *net, struct fib6_result *res, if (fl6->mp_hash <= atomic_read(&match->fib6_nh->fib_nh_upper_bound)) goto out; - list_for_each_entry_safe(sibling, next_sibling, &match->fib6_siblings, - fib6_siblings) { + list_for_each_entry_rcu(sibling, &match->fib6_siblings, + fib6_siblings) { const struct fib6_nh *nh = sibling->fib6_nh; int nh_upper_bound; @@ -5195,14 +5195,18 @@ static void ip6_route_mpath_notify(struct fib6_info *rt, * nexthop. Since sibling routes are always added at the end of * the list, find the first sibling of the last route appended */ + rcu_read_lock(); + if ((nlflags & NLM_F_APPEND) && rt_last && rt_last->fib6_nsiblings) { - rt = list_first_entry(&rt_last->fib6_siblings, - struct fib6_info, - fib6_siblings); + rt = list_first_or_null_rcu(&rt_last->fib6_siblings, + struct fib6_info, + fib6_siblings); } if (rt) inet6_rt_notify(RTM_NEWROUTE, rt, info, nlflags); + + rcu_read_unlock(); } static bool ip6_route_mpath_should_notify(const struct fib6_info *rt) @@ -5547,17 +5551,21 @@ static size_t rt6_nlmsg_size(struct fib6_info *f6i) nexthop_for_each_fib6_nh(f6i->nh, rt6_nh_nlmsg_size, &nexthop_len); } else { - struct fib6_info *sibling, *next_sibling; struct fib6_nh *nh = f6i->fib6_nh; + struct fib6_info *sibling; nexthop_len = 0; if (f6i->fib6_nsiblings) { rt6_nh_nlmsg_size(nh, &nexthop_len); - list_for_each_entry_safe(sibling, next_sibling, - &f6i->fib6_siblings, fib6_siblings) { + rcu_read_lock(); + + list_for_each_entry_rcu(sibling, &f6i->fib6_siblings, + fib6_siblings) { rt6_nh_nlmsg_size(sibling->fib6_nh, &nexthop_len); } + + rcu_read_unlock(); } nexthop_len += lwtunnel_get_encap_size(nh->fib_nh_lws); } @@ -5721,7 +5729,7 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb, lwtunnel_fill_encap(skb, dst->lwtstate, RTA_ENCAP, RTA_ENCAP_TYPE) < 0) goto nla_put_failure; } else if (rt->fib6_nsiblings) { - struct fib6_info *sibling, *next_sibling; + struct fib6_info *sibling; struct nlattr *mp; mp = nla_nest_start_noflag(skb, RTA_MULTIPATH); @@ -5733,14 +5741,21 @@ static int rt6_fill_node(struct net *net, struct sk_buff *skb, 0) < 0) goto nla_put_failure; - list_for_each_entry_safe(sibling, next_sibling, - &rt->fib6_siblings, fib6_siblings) { + rcu_read_lock(); + + list_for_each_entry_rcu(sibling, &rt->fib6_siblings, + fib6_siblings) { if (fib_add_nexthop(skb, &sibling->fib6_nh->nh_common, sibling->fib6_nh->fib_nh_weight, - AF_INET6, 0) < 0) + AF_INET6, 0) < 0) { + rcu_read_unlock(); + goto nla_put_failure; + } } + rcu_read_unlock(); + nla_nest_end(skb, mp); } else if (rt->nh) { if (nla_put_u32(skb, RTA_NH_ID, rt->nh->id)) @@ -6177,7 +6192,7 @@ void inet6_rt_notify(int event, struct fib6_info *rt, struct nl_info *info, err = -ENOBUFS; seq = info->nlh ? info->nlh->nlmsg_seq : 0; - skb = nlmsg_new(rt6_nlmsg_size(rt), gfp_any()); + skb = nlmsg_new(rt6_nlmsg_size(rt), GFP_ATOMIC); if (!skb) goto errout; @@ -6190,7 +6205,7 @@ void inet6_rt_notify(int event, struct fib6_info *rt, struct nl_info *info, goto errout; } rtnl_notify(skb, net, info->portid, RTNLGRP_IPV6_ROUTE, - info->nlh, gfp_any()); + info->nlh, GFP_ATOMIC); return; errout: rtnl_set_sk_err(net, RTNLGRP_IPV6_ROUTE, err); diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile index 649f1fe0dc46..88cbac27aa10 100644 --- a/tools/testing/selftests/net/Makefile +++ b/tools/testing/selftests/net/Makefile @@ -96,6 +96,7 @@ TEST_PROGS += fdb_flush.sh TEST_PROGS += fq_band_pktlimit.sh TEST_PROGS += vlan_hw_filter.sh TEST_PROGS += bpf_offload.py +TEST_PROGS += ipv6_route_update_soft_lockup.sh # YNL files, must be before "include ..lib.mk" EXTRA_CLEAN += $(OUTPUT)/libynl.a diff --git a/tools/testing/selftests/net/ipv6_route_update_soft_lockup.sh b/tools/testing/selftests/net/ipv6_route_update_soft_lockup.sh new file mode 100755 index 000000000000..c61a7a8352cf --- /dev/null +++ b/tools/testing/selftests/net/ipv6_route_update_soft_lockup.sh @@ -0,0 +1,262 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# +# Testing for potential kernel soft lockup during IPv6 routing table +# refresh under heavy outgoing IPv6 traffic. If a kernel soft lockup +# occurs, a kernel panic will be triggered to prevent associated issues. +# +# +# Test Environment Layout +# +# ┌----------------┐ ┌----------------┐ +# | SOURCE_NS | | SINK_NS | +# | NAMESPACE | | NAMESPACE | +# |(iperf3 clients)| |(iperf3 servers)| +# | | | | +# | | | | +# | ┌-----------| nexthops |---------┐ | +# | |veth_source|<--------------------------------------->|veth_sink|<┐ | +# | └-----------|2001:0DB8:1::0:1/96 2001:0DB8:1::1:1/96 |---------┘ | | +# | | ^ 2001:0DB8:1::1:2/96 | | | +# | | . . | fwd | | +# | ┌---------┐ | . . | | | +# | | IPv6 | | . . | V | +# | | routing | | . 2001:0DB8:1::1:80/96| ┌-----┐ | +# | | table | | . | | lo | | +# | | nexthop | | . └--------┴-----┴-┘ +# | | update | | ............................> 2001:0DB8:2::1:1/128 +# | └-------- ┘ | +# └----------------┘ +# +# The test script sets up two network namespaces, source_ns and sink_ns, +# connected via a veth link. Within source_ns, it continuously updates the +# IPv6 routing table by flushing and inserting IPV6_NEXTHOP_ADDR_COUNT nexthop +# IPs destined for SINK_LOOPBACK_IP_ADDR in sink_ns. This refresh occurs at a +# rate of 1/ROUTING_TABLE_REFRESH_PERIOD per second for TEST_DURATION seconds. +# +# Simultaneously, multiple iperf3 clients within source_ns generate heavy +# outgoing IPv6 traffic. Each client is assigned a unique port number starting +# at 5000 and incrementing sequentially. Each client targets a unique iperf3 +# server running in sink_ns, connected to the SINK_LOOPBACK_IFACE interface +# using the same port number. +# +# The number of iperf3 servers and clients is set to half of the total +# available cores on each machine. +# +# NOTE: We have tested this script on machines with various CPU specifications, +# ranging from lower to higher performance as listed below. The test script +# effectively triggered a kernel soft lockup on machines running an unpatched +# kernel in under a minute: +# +# - 1x Intel Xeon E-2278G 8-Core Processor @ 3.40GHz +# - 1x Intel Xeon E-2378G Processor 8-Core @ 2.80GHz +# - 1x AMD EPYC 7401P 24-Core Processor @ 2.00GHz +# - 1x AMD EPYC 7402P 24-Core Processor @ 2.80GHz +# - 2x Intel Xeon Gold 5120 14-Core Processor @ 2.20GHz +# - 1x Ampere Altra Q80-30 80-Core Processor @ 3.00GHz +# - 2x Intel Xeon Gold 5120 14-Core Processor @ 2.20GHz +# - 2x Intel Xeon Silver 4214 24-Core Processor @ 2.20GHz +# - 1x AMD EPYC 7502P 32-Core @ 2.50GHz +# - 1x Intel Xeon Gold 6314U 32-Core Processor @ 2.30GHz +# - 2x Intel Xeon Gold 6338 32-Core Processor @ 2.00GHz +# +# On less performant machines, you may need to increase the TEST_DURATION +# parameter to enhance the likelihood of encountering a race condition leading +# to a kernel soft lockup and avoid a false negative result. +# +# NOTE: The test may not produce the expected result in virtualized +# environments (e.g., qemu) due to differences in timing and CPU handling, +# which can affect the conditions needed to trigger a soft lockup. + +source lib.sh +source net_helper.sh + +TEST_DURATION=300 +ROUTING_TABLE_REFRESH_PERIOD=0.01 + +IPERF3_BITRATE="300m" + + +IPV6_NEXTHOP_ADDR_COUNT="128" +IPV6_NEXTHOP_ADDR_MASK="96" +IPV6_NEXTHOP_PREFIX="2001:0DB8:1" + + +SOURCE_TEST_IFACE="veth_source" +SOURCE_TEST_IP_ADDR="2001:0DB8:1::0:1/96" + +SINK_TEST_IFACE="veth_sink" +# ${SINK_TEST_IFACE} is populated with the following range of IPv6 addresses: +# 2001:0DB8:1::1:1 to 2001:0DB8:1::1:${IPV6_NEXTHOP_ADDR_COUNT} +SINK_LOOPBACK_IFACE="lo" +SINK_LOOPBACK_IP_MASK="128" +SINK_LOOPBACK_IP_ADDR="2001:0DB8:2::1:1" + +nexthop_ip_list="" +termination_signal="" +kernel_softlokup_panic_prev_val="" + +terminate_ns_processes_by_pattern() { + local ns=$1 + local pattern=$2 + + for pid in $(ip netns pids ${ns}); do + [ -e /proc/$pid/cmdline ] && grep -qe "${pattern}" /proc/$pid/cmdline && kill -9 $pid + done +} + +cleanup() { + echo "info: cleaning up namespaces and terminating all processes within them..." + + + # Terminate iperf3 instances running in the source_ns. To avoid race + # conditions, first iterate over the PIDs and terminate those + # associated with the bash shells running the + # `while true; do iperf3 -c ...; done` loops. In a second iteration, + # terminate the individual `iperf3 -c ...` instances. + terminate_ns_processes_by_pattern ${source_ns} while + terminate_ns_processes_by_pattern ${source_ns} iperf3 + + # Repeat the same process for sink_ns + terminate_ns_processes_by_pattern ${sink_ns} while + terminate_ns_processes_by_pattern ${sink_ns} iperf3 + + # Check if any iperf3 instances are still running. This could happen + # if a core has entered an infinite loop and the timeout for detecting + # the soft lockup has not expired, but either the test interval has + # already elapsed or the test was terminated manually (e.g., with ^C) + for pid in $(ip netns pids ${source_ns}); do + if [ -e /proc/$pid/cmdline ] && grep -qe 'iperf3' /proc/$pid/cmdline; then + echo "FAIL: unable to terminate some iperf3 instances. Soft lockup is underway. A kernel panic is on the way!" + exit ${ksft_fail} + fi + done + + if [ "$termination_signal" == "SIGINT" ]; then + echo "SKIP: Termination due to ^C (SIGINT)" + elif [ "$termination_signal" == "SIGALRM" ]; then + echo "PASS: No kernel soft lockup occurred during this ${TEST_DURATION} second test" + fi + + cleanup_ns ${source_ns} ${sink_ns} + + sysctl -qw kernel.softlockup_panic=${kernel_softlokup_panic_prev_val} +} + +setup_prepare() { + setup_ns source_ns sink_ns + + ip -n ${source_ns} link add name ${SOURCE_TEST_IFACE} type veth peer name ${SINK_TEST_IFACE} netns ${sink_ns} + + # Setting up the Source namespace + ip -n ${source_ns} addr add ${SOURCE_TEST_IP_ADDR} dev ${SOURCE_TEST_IFACE} + ip -n ${source_ns} link set dev ${SOURCE_TEST_IFACE} qlen 10000 + ip -n ${source_ns} link set dev ${SOURCE_TEST_IFACE} up + ip netns exec ${source_ns} sysctl -qw net.ipv6.fib_multipath_hash_policy=1 + + # Setting up the Sink namespace + ip -n ${sink_ns} addr add ${SINK_LOOPBACK_IP_ADDR}/${SINK_LOOPBACK_IP_MASK} dev ${SINK_LOOPBACK_IFACE} + ip -n ${sink_ns} link set dev ${SINK_LOOPBACK_IFACE} up + ip netns exec ${sink_ns} sysctl -qw net.ipv6.conf.${SINK_LOOPBACK_IFACE}.forwarding=1 + + ip -n ${sink_ns} link set ${SINK_TEST_IFACE} up + ip netns exec ${sink_ns} sysctl -qw net.ipv6.conf.${SINK_TEST_IFACE}.forwarding=1 + + + # Populate nexthop IPv6 addresses on the test interface in the sink_ns + echo "info: populating ${IPV6_NEXTHOP_ADDR_COUNT} IPv6 addresses on the ${SINK_TEST_IFACE} interface ..." + for IP in $(seq 1 ${IPV6_NEXTHOP_ADDR_COUNT}); do + ip -n ${sink_ns} addr add ${IPV6_NEXTHOP_PREFIX}::$(printf "1:%x" "${IP}")/${IPV6_NEXTHOP_ADDR_MASK} dev ${SINK_TEST_IFACE}; + done + + # Preparing list of nexthops + for IP in $(seq 1 ${IPV6_NEXTHOP_ADDR_COUNT}); do + nexthop_ip_list=$nexthop_ip_list" nexthop via ${IPV6_NEXTHOP_PREFIX}::$(printf "1:%x" $IP) dev ${SOURCE_TEST_IFACE} weight 1" + done +} + + +test_soft_lockup_during_routing_table_refresh() { + # Start num_of_iperf_servers iperf3 servers in the sink_ns namespace, + # each listening on ports starting at 5001 and incrementing + # sequentially. Since iperf3 instances may terminate unexpectedly, a + # while loop is used to automatically restart them in such cases. + echo "info: starting ${num_of_iperf_servers} iperf3 servers in the sink_ns namespace ..." + for i in $(seq 1 ${num_of_iperf_servers}); do + cmd="iperf3 --bind ${SINK_LOOPBACK_IP_ADDR} -s -p $(printf '5%03d' ${i}) --rcv-timeout 200 &>/dev/null" + ip netns exec ${sink_ns} bash -c "while true; do ${cmd}; done &" &>/dev/null + done + + # Wait for the iperf3 servers to be ready + for i in $(seq ${num_of_iperf_servers}); do + port=$(printf '5%03d' ${i}); + wait_local_port_listen ${sink_ns} ${port} tcp + done + + # Continuously refresh the routing table in the background within + # the source_ns namespace + ip netns exec ${source_ns} bash -c " + while \$(ip netns list | grep -q ${source_ns}); do + ip -6 route add ${SINK_LOOPBACK_IP_ADDR}/${SINK_LOOPBACK_IP_MASK} ${nexthop_ip_list}; + sleep ${ROUTING_TABLE_REFRESH_PERIOD}; + ip -6 route delete ${SINK_LOOPBACK_IP_ADDR}/${SINK_LOOPBACK_IP_MASK}; + done &" + + # Start num_of_iperf_servers iperf3 clients in the source_ns namespace, + # each sending TCP traffic on sequential ports starting at 5001. + # Since iperf3 instances may terminate unexpectedly (e.g., if the route + # to the server is deleted in the background during a route refresh), a + # while loop is used to automatically restart them in such cases. + echo "info: starting ${num_of_iperf_servers} iperf3 clients in the source_ns namespace ..." + for i in $(seq 1 ${num_of_iperf_servers}); do + cmd="iperf3 -c ${SINK_LOOPBACK_IP_ADDR} -p $(printf '5%03d' ${i}) --length 64 --bitrate ${IPERF3_BITRATE} -t 0 --connect-timeout 150 &>/dev/null" + ip netns exec ${source_ns} bash -c "while true; do ${cmd}; done &" &>/dev/null + done + + echo "info: IPv6 routing table is being updated at the rate of $(echo "1/${ROUTING_TABLE_REFRESH_PERIOD}" | bc)/s for ${TEST_DURATION} seconds ..." + echo "info: A kernel soft lockup, if detected, results in a kernel panic!" + + wait +} + +# Make sure 'iperf3' is installed, skip the test otherwise +if [ ! -x "$(command -v "iperf3")" ]; then + echo "SKIP: 'iperf3' is not installed. Skipping the test." + exit ${ksft_skip} +fi + +# Determine the number of cores on the machine +num_of_iperf_servers=$(( $(nproc)/2 )) + +# Check if we are running on a multi-core machine, skip the test otherwise +if [ "${num_of_iperf_servers}" -eq 0 ]; then + echo "SKIP: This test is not valid on a single core machine!" + exit ${ksft_skip} +fi + +# Since the kernel soft lockup we're testing causes at least one core to enter +# an infinite loop, destabilizing the host and likely affecting subsequent +# tests, we trigger a kernel panic instead of reporting a failure and +# continuing +kernel_softlokup_panic_prev_val=$(sysctl -n kernel.softlockup_panic) +sysctl -qw kernel.softlockup_panic=1 + +handle_sigint() { + termination_signal="SIGINT" + cleanup + exit ${ksft_skip} +} + +handle_sigalrm() { + termination_signal="SIGALRM" + cleanup + exit ${ksft_pass} +} + +trap handle_sigint SIGINT +trap handle_sigalrm SIGALRM + +(sleep ${TEST_DURATION} && kill -s SIGALRM $$)& + +setup_prepare +test_soft_lockup_during_routing_table_refresh -- 2.43.0

11 months, 3 weeks

3
3
0 0

[PATCH v4] selftests: clone3: Use the capget and capset syscall directly

by zhouyuhang

From: zhouyuhang <zhouyuhang(a)kylinos.cn> The libcap commit aca076443591 ("Make cap_t operations thread safe.") added a __u8 mutex at the beginning of the struct _cap_struct, it changes the offset of the members in the structure that breaks the assumption made in the "struct libcap" definition in clone3_cap_checkpoint_restore.c. This causes the call to cap_set_proc here to fail with error code EPERM, and the output is as follows: # RUN global.clone3_cap_checkpoint_restore ... # clone3() syscall supported # clone3_cap_checkpoint_restore.c:151:clone3_cap_checkpoint_restore:Child has PID 130508 cap_set_proc: Operation not permitted # clone3_cap_checkpoint_restore.c:160:clone3_cap_checkpoint_restore:Expected set_capability() (-1) == 0 (0) # clone3_cap_checkpoint_restore.c:161:clone3_cap_checkpoint_restore:Could not set CAP_CHECKPOINT_RESTORE # clone3_cap_checkpoint_restore: Test terminated by assertion # FAIL global.clone3_cap_checkpoint_restore Changing to using capget and capset syscall directly here can fix this error, just like what the commit 663af70aabb7 ("bpf: selftests: Add helpers to directly use the capget and capset syscall") does. The output is as follows: # RUN global.clone3_cap_checkpoint_restore ... # clone3() syscall supported # clone3_cap_checkpoint_restore.c:160:clone3_cap_checkpoint_restore:Child has PID 23708 # clone3_cap_checkpoint_restore.c:91:clone3_cap_checkpoint_restore:[23707] Trying clone3() with CLONE_SET_TID to 23708 # clone3_cap_checkpoint_restore.c:58:clone3_cap_checkpoint_restore:Operation not permitted - Failed to create new process # clone3_cap_checkpoint_restore.c:93:clone3_cap_checkpoint_restore:[23707] clone3() with CLONE_SET_TID 23708 says:-1 # clone3_cap_checkpoint_restore.c:91:clone3_cap_checkpoint_restore:[23707] Trying clone3() with CLONE_SET_TID to 23708 # clone3_cap_checkpoint_restore.c:73:clone3_cap_checkpoint_restore:I am the parent (23707). My child's pid is 23708 # clone3_cap_checkpoint_restore.c:66:clone3_cap_checkpoint_restore:I am the child, my PID is 23708 (expected 23708) # clone3_cap_checkpoint_restore.c:93:clone3_cap_checkpoint_restore:[23707] clone3() with CLONE_SET_TID 23708 says:0 # OK global.clone3_cap_checkpoint_restore ok 1 global.clone3_cap_checkpoint_restore # PASSED: 1 / 1 tests passed. Signed-off-by: zhouyuhang <zhouyuhang(a)kylinos.cn> --- v4: * Add some comments and modify the output and return value when set_capability fails v3: * Remove locally declared system calls and retained the - lcap in the Makefile. v2: * Move locally declared system calls to header file. v1: * Directly using capget and capset and declare them locally. --- .../clone3/clone3_cap_checkpoint_restore.c | 77 +++++++++++-------- 1 file changed, 43 insertions(+), 34 deletions(-) diff --git a/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c b/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c index 3c196fa86c99..076f9d4cce60 100644 --- a/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c +++ b/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c @@ -27,6 +27,13 @@ #include "../kselftest_harness.h" #include "clone3_selftests.h" +/* + * Prevent not being defined in the header file + */ +#ifndef CAP_CHECKPOINT_RESTORE +#define CAP_CHECKPOINT_RESTORE 40 +#endif + static void child_exit(int ret) { fflush(stdout); @@ -87,47 +94,49 @@ static int test_clone3_set_tid(struct __test_metadata *_metadata, return ret; } -struct libcap { - struct __user_cap_header_struct hdr; +static int set_capability(struct __test_metadata *_metadata) +{ struct __user_cap_data_struct data[2]; -}; -static int set_capability(void) -{ - cap_value_t cap_values[] = { CAP_SETUID, CAP_SETGID }; - struct libcap *cap; - int ret = -1; - cap_t caps; - - caps = cap_get_proc(); - if (!caps) { - perror("cap_get_proc"); - return -1; - } + /* + * Only _LINUX_CAPABILITY_VERSION_3 can be used here. + * _LINUX_CAPABILITY_VERSION_1 represents use 32-bit capabilities, + * using it will cause CAP_CHECKPOINT_RESTORE to not be set. + * _LINUX_CAPABILITY_VERSION_2 has already been deprecated. + */ + struct __user_cap_header_struct hdr = { + .version = _LINUX_CAPABILITY_VERSION_3, + }; - /* Drop all capabilities */ - if (cap_clear(caps)) { - perror("cap_clear"); - goto out; + /* + * CAP_CHECKPOINT_RESTORE is greater than 31, so we need two u32. + * cap0 is the lower 32bit and cap1 is the higher 32bit, they will + * be combined into a u64 in mk_kernel_cap. + */ + __u32 cap0 = 1 << CAP_SETUID | 1 << CAP_SETGID; + __u32 cap1 = 1 << (CAP_CHECKPOINT_RESTORE - 32); + int ret; + + ret = capget(&hdr, data); + if (ret) { + TH_LOG("%s - Failed to get capability", strerror(errno)); + return -errno; } - cap_set_flag(caps, CAP_EFFECTIVE, 2, cap_values, CAP_SET); - cap_set_flag(caps, CAP_PERMITTED, 2, cap_values, CAP_SET); + /* Drop all capabilities */ + memset(&data, 0, sizeof(data)); - cap = (struct libcap *) caps; + data[0].effective |= cap0; + data[0].permitted |= cap0; - /* 40 -> CAP_CHECKPOINT_RESTORE */ - cap->data[1].effective |= 1 << (40 - 32); - cap->data[1].permitted |= 1 << (40 - 32); + data[1].effective |= cap1; + data[1].permitted |= cap1; - if (cap_set_proc(caps)) { - perror("cap_set_proc"); - goto out; + ret = capset(&hdr, data); + if (ret) { + TH_LOG("%s - Failed to set capability", strerror(errno)); + return -errno; } - ret = 0; -out: - if (cap_free(caps)) - perror("cap_free"); return ret; } @@ -157,7 +166,7 @@ TEST(clone3_cap_checkpoint_restore) /* After the child has finished, its PID should be free. */ set_tid[0] = pid; - ASSERT_EQ(set_capability(), 0) + ASSERT_EQ(set_capability(_metadata), 0) TH_LOG("Could not set CAP_CHECKPOINT_RESTORE"); ASSERT_EQ(prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0), 0); @@ -169,7 +178,7 @@ TEST(clone3_cap_checkpoint_restore) set_tid[0] = pid; /* This would fail without CAP_CHECKPOINT_RESTORE */ ASSERT_EQ(test_clone3_set_tid(_metadata, set_tid, 1), -EPERM); - ASSERT_EQ(set_capability(), 0) + ASSERT_EQ(set_capability(_metadata), 0) TH_LOG("Could not set CAP_CHECKPOINT_RESTORE"); /* This should work as we have CAP_CHECKPOINT_RESTORE as non-root */ ASSERT_EQ(test_clone3_set_tid(_metadata, set_tid, 1), 0); -- 2.27.0

11 months, 3 weeks

1
0
0 0

[PATCH] KVM: selftests: memslot_perf_test: increase guest sync timeout

by Maxim Levitsky

When memslot_perf_test is run nested, first iteration of test_memslot_rw_loop testcase, sometimes takes more than 2 seconds due to build of shadow page tables. Following iterations are fast. To be on the safe side, bump the timeout to 10 seconds. Signed-off-by: Maxim Levitsky <mlevitsk(a)redhat.com> --- tools/testing/selftests/kvm/memslot_perf_test.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/kvm/memslot_perf_test.c b/tools/testing/selftests/kvm/memslot_perf_test.c index 893366982f77b..e9189cbed4bb6 100644 --- a/tools/testing/selftests/kvm/memslot_perf_test.c +++ b/tools/testing/selftests/kvm/memslot_perf_test.c @@ -415,7 +415,7 @@ static bool _guest_should_exit(void) */ static noinline void host_perform_sync(struct sync_area *sync) { - alarm(2); + alarm(10); atomic_store_explicit(&sync->sync_flag, true, memory_order_release); while (atomic_load_explicit(&sync->sync_flag, memory_order_acquire)) -- 2.26.3

11 months, 3 weeks

3
3
0 0

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Linux-kselftest-mirror November 2024