This extension allows to use F_UNLCK on query, which currently returns
EINVAL. Instead it can be used to query the locks on a particular fd -
something that is not currently possible. The basic idea is that on
F_OFD_GETLK, F_UNLCK would "conflict" with (or query) any types of the
lock on the same fd, and ignore any locks on other fds.
Use-cases:
1. CRIU-alike scenario when you want to read the locking info from an
fd for the later reconstruction. This can now be done by setting
l_start and l_len to 0 to cover entire file range, and do F_OFD_GETLK.
In the loop you need to advance l_start past the returned lock ranges,
to eventually collect all locked ranges.
2. Implementing the lock checking/enforcing policy.
Say you want to implement an "auditor" module in your program,
that checks that the I/O is done only after the proper locking is
applied on a file region. In this case you need to know if the
particular region is locked on that fd, and if so - with what type
of the lock. If you would do that currently (without this extension)
then you can only check for the write locks, and for that you need to
probe the lock on your fd and then open the same file via another fd and
probe there. That way you can identify the write lock on a particular
fd, but such trick is non-atomic and complex. As for finding out the
read lock on a particular fd - impossible.
This extension allows to do such queries without any extra efforts.
3. Implementing the mandatory locking policy.
Suppose you want to make a policy where the write lock inhibits any
unlocked readers and writers. Currently you need to check if the
write lock is present on some other fd, and if it is not there - allow
the I/O operation. But because the write lock can appear at any moment,
you need to do that under some global lock, which can be released only
when the I/O operation is finished.
With the proposed extension you can instead just check the write lock
on your own fd first, and if it is there - allow the I/O operation on
that fd without using any global lock. Only if there is no write lock
on this fd, then you need to take global lock and check for a write
lock on other fds.
The second patch adds a test-case for OFD locks.
It tests both the generic things and the proposed extension.
The third patch is a proposed man page update for fcntl(2)
(not for the linux source tree)
Changes in v2:
- Dropped the l_pid extension patch and updated test-case accordingly.
Stas Sergeev (2):
fs/locks: F_UNLCK extension for F_OFD_GETLK
selftests: add OFD lock tests
fs/locks.c | 23 +++-
tools/testing/selftests/locking/Makefile | 2 +
tools/testing/selftests/locking/ofdlocks.c | 132 +++++++++++++++++++++
3 files changed, 154 insertions(+), 3 deletions(-)
create mode 100644 tools/testing/selftests/locking/ofdlocks.c
CC: Jeff Layton <jlayton(a)kernel.org>
CC: Chuck Lever <chuck.lever(a)oracle.com>
CC: Alexander Viro <viro(a)zeniv.linux.org.uk>
CC: Christian Brauner <brauner(a)kernel.org>
CC: linux-fsdevel(a)vger.kernel.org
CC: linux-kernel(a)vger.kernel.org
CC: Shuah Khan <shuah(a)kernel.org>
CC: linux-kselftest(a)vger.kernel.org
CC: linux-api(a)vger.kernel.org
--
2.39.2
*Changes in v27:*
- Handle review comments and minor improvements
- Add performance improvement patch on top with test for easy review
*Changes in v26:*
- Code re-structurring and API changes in PAGEMAP_IOCTL
*Changes in v25*:
- Do proper filtering on hole as well (hole got missed earlier)
*Changes in v24*:
- Rebase on top of next-20230710
- Place WP markers in case of hole as well
*Changes in v23*:
- Set vec_buf_index in loop only when vec_buf_index is set
- Return -EFAULT instead of -EINVAL if vec is NULL
- Correctly return the walk ending address to the page granularity
*Changes in v22*:
- Interface change:
- Replace [start start + len) with [start, end)
- Return the ending address of the address walk in start
*Changes in v21*:
- Abort walk instead of returning error if WP is to be performed on
partial hugetlb
*Changes in v20*
- Correct PAGE_IS_FILE and add PAGE_IS_PFNZERO
*Changes in v19*
- Minor changes and interface updates
*Changes in v18*
- Rebase on top of next-20230613
- Minor updates
*Changes in v17*
- Rebase on top of next-20230606
- Minor improvements in PAGEMAP_SCAN IOCTL patch
*Changes in v16*
- Fix a corner case
- Add exclusive PM_SCAN_OP_WP back
*Changes in v15*
- Build fix (Add missed build fix in RESEND)
*Changes in v14*
- Fix build error caused by #ifdef added at last minute in some configs
*Changes in v13*
- Rebase on top of next-20230414
- Give-up on using uffd_wp_range() and write new helpers, flush tlb only
once
*Changes in v12*
- Update and other memory types to UFFD_FEATURE_WP_ASYNC
- Rebaase on top of next-20230406
- Review updates
*Changes in v11*
- Rebase on top of next-20230307
- Base patches on UFFD_FEATURE_WP_UNPOPULATED
- Do a lot of cosmetic changes and review updates
- Remove ENGAGE_WP + !GET operation as it can be performed with
UFFDIO_WRITEPROTECT
*Changes in v10*
- Add specific condition to return error if hugetlb is used with wp
async
- Move changes in tools/include/uapi/linux/fs.h to separate patch
- Add documentation
*Changes in v9:*
- Correct fault resolution for userfaultfd wp async
- Fix build warnings and errors which were happening on some configs
- Simplify pagemap ioctl's code
*Changes in v8:*
- Update uffd async wp implementation
- Improve PAGEMAP_IOCTL implementation
*Changes in v7:*
- Add uffd wp async
- Update the IOCTL to use uffd under the hood instead of soft-dirty
flags
*Motivation*
The real motivation for adding PAGEMAP_SCAN IOCTL is to emulate Windows
GetWriteWatch() and ResetWriteWatch() syscalls [1]. The GetWriteWatch()
retrieves the addresses of the pages that are written to in a region of
virtual memory.
This syscall is used in Windows applications and games etc. This syscall is
being emulated in pretty slow manner in userspace. Our purpose is to
enhance the kernel such that we translate it efficiently in a better way.
Currently some out of tree hack patches are being used to efficiently
emulate it in some kernels. We intend to replace those with these patches.
So the whole gaming on Linux can effectively get benefit from this. It
means there would be tons of users of this code.
CRIU use case [2] was mentioned by Andrei and Danylo:
> Use cases for migrating sparse VMAs are binaries sanitized with ASAN,
> MSAN or TSAN [3]. All of these sanitizers produce sparse mappings of
> shadow memory [4]. Being able to migrate such binaries allows to highly
> reduce the amount of work needed to identify and fix post-migration
> crashes, which happen constantly.
Andrei's defines the following uses of this code:
* it is more granular and allows us to track changed pages more
effectively. The current interface can clear dirty bits for the entire
process only. In addition, reading info about pages is a separate
operation. It means we must freeze the process to read information
about all its pages, reset dirty bits, only then we can start dumping
pages. The information about pages becomes more and more outdated,
while we are processing pages. The new interface solves both these
downsides. First, it allows us to read pte bits and clear the
soft-dirty bit atomically. It means that CRIU will not need to freeze
processes to pre-dump their memory. Second, it clears soft-dirty bits
for a specified region of memory. It means CRIU will have actual info
about pages to the moment of dumping them.
* The new interface has to be much faster because basic page filtering
is happening in the kernel. With the old interface, we have to read
pagemap for each page.
*Implementation Evolution (Short Summary)*
From the definition of GetWriteWatch(), we feel like kernel's soft-dirty
feature can be used under the hood with some additions like:
* reset soft-dirty flag for only a specific region of memory instead of
clearing the flag for the entire process
* get and clear soft-dirty flag for a specific region atomically
So we decided to use ioctl on pagemap file to read or/and reset soft-dirty
flag. But using soft-dirty flag, sometimes we get extra pages which weren't
even written. They had become soft-dirty because of VMA merging and
VM_SOFTDIRTY flag. This breaks the definition of GetWriteWatch(). We were
able to by-pass this short coming by ignoring VM_SOFTDIRTY until David
reported that mprotect etc messes up the soft-dirty flag while ignoring
VM_SOFTDIRTY [5]. This wasn't happening until [6] got introduced. We
discussed if we can revert these patches. But we could not reach to any
conclusion. So at this point, I made couple of tries to solve this whole
VM_SOFTDIRTY issue by correcting the soft-dirty implementation:
* [7] Correct the bug fixed wrongly back in 2014. It had potential to cause
regression. We left it behind.
* [8] Keep a list of soft-dirty part of a VMA across splits and merges. I
got the reply don't increase the size of the VMA by 8 bytes.
At this point, we left soft-dirty considering it is too much delicate and
userfaultfd [9] seemed like the only way forward. From there onward, we
have been basing soft-dirty emulation on userfaultfd wp feature where
kernel resolves the faults itself when WP_ASYNC feature is used. It was
straight forward to add WP_ASYNC feature in userfautlfd. Now we get only
those pages dirty or written-to which are really written in reality. (PS
There is another WP_UNPOPULATED userfautfd feature is required which is
needed to avoid pre-faulting memory before write-protecting [9].)
All the different masks were added on the request of CRIU devs to create
interface more generic and better.
[1] https://learn.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-…
[2] https://lore.kernel.org/all/20221014134802.1361436-1-mdanylo@google.com
[3] https://github.com/google/sanitizers
[4] https://github.com/google/sanitizers/wiki/AddressSanitizerAlgorithm#64-bit
[5] https://lore.kernel.org/all/bfcae708-db21-04b4-0bbe-712badd03071@redhat.com
[6] https://lore.kernel.org/all/20220725142048.30450-1-peterx@redhat.com/
[7] https://lore.kernel.org/all/20221122115007.2787017-1-usama.anjum@collabora.…
[8] https://lore.kernel.org/all/20221220162606.1595355-1-usama.anjum@collabora.…
[9] https://lore.kernel.org/all/20230306213925.617814-1-peterx@redhat.com
[10] https://lore.kernel.org/all/20230125144529.1630917-1-mdanylo@google.com
* Original Cover letter from v8*
Hello,
Note:
Soft-dirty pages and pages which have been written-to are synonyms. As
kernel already has soft-dirty feature inside which we have given up to
use, we are using written-to terminology while using UFFD async WP under
the hood.
It is possible to find and clear soft-dirty pages entirely in userspace.
But it isn't efficient:
- The mprotect and SIGSEGV handler for bookkeeping
- The userfaultfd wp (synchronous) with the handler for bookkeeping
Some benchmarks can be seen here[1]. This series adds features that weren't
present earlier:
- There is no atomic get soft-dirty/Written-to status and clear present in
the kernel.
- The pages which have been written-to can not be found in accurate way.
(Kernel's soft-dirty PTE bit + sof_dirty VMA bit shows more soft-dirty
pages than there actually are.)
Historically, soft-dirty PTE bit tracking has been used in the CRIU
project. The procfs interface is enough for finding the soft-dirty bit
status and clearing the soft-dirty bit of all the pages of a process.
We have the use case where we need to track the soft-dirty PTE bit for
only specific pages on-demand. We need this tracking and clear mechanism
of a region of memory while the process is running to emulate the
getWriteWatch() syscall of Windows.
*(Moved to using UFFD instead of soft-dirty feature to find pages which
have been written-to from v7 patch series)*:
Stop using the soft-dirty flags for finding which pages have been
written to. It is too delicate and wrong as it shows more soft-dirty
pages than the actual soft-dirty pages. There is no interest in
correcting it [2][3] as this is how the feature was written years ago.
It shouldn't be updated to changed behaviour. Peter Xu has suggested
using the async version of the UFFD WP [4] as it is based inherently
on the PTEs.
So in this patch series, I've added a new mode to the UFFD which is
asynchronous version of the write protect. When this variant of the
UFFD WP is used, the page faults are resolved automatically by the
kernel. The pages which have been written-to can be found by reading
pagemap file (!PM_UFFD_WP). This feature can be used successfully to
find which pages have been written to from the time the pages were
write protected. This works just like the soft-dirty flag without
showing any extra pages which aren't soft-dirty in reality.
The information related to pages if the page is file mapped, present and
swapped is required for the CRIU project [5][6]. The addition of the
required mask, any mask, excluded mask and return masks are also required
for the CRIU project [5].
The IOCTL returns the addresses of the pages which match the specific
masks. The page addresses are returned in struct page_region in a compact
form. The max_pages is needed to support a use case where user only wants
to get a specific number of pages. So there is no need to find all the
pages of interest in the range when max_pages is specified. The IOCTL
returns when the maximum number of the pages are found. The max_pages is
optional. If max_pages is specified, it must be equal or greater than the
vec_size. This restriction is needed to handle worse case when one
page_region only contains info of one page and it cannot be compacted.
This is needed to emulate the Windows getWriteWatch() syscall.
The patch series include the detailed selftest which can be used as an
example for the uffd async wp test and PAGEMAP_IOCTL. It shows the
interface usages as well.
[1] https://lore.kernel.org/lkml/54d4c322-cd6e-eefd-b161-2af2b56aae24@collabora…
[2] https://lore.kernel.org/all/20221220162606.1595355-1-usama.anjum@collabora.…
[3] https://lore.kernel.org/all/20221122115007.2787017-1-usama.anjum@collabora.…
[4] https://lore.kernel.org/all/Y6Hc2d+7eTKs7AiH@x1n
[5] https://lore.kernel.org/all/YyiDg79flhWoMDZB@gmail.com/
[6] https://lore.kernel.org/all/20221014134802.1361436-1-mdanylo@google.com/
Regards,
Muhammad Usama Anjum
Muhammad Usama Anjum (5):
fs/proc/task_mmu: Implement IOCTL to get and optionally clear info
about PTEs
fs/proc/task_mmu: Add fast paths to get/clear PAGE_IS_WRITTEN flag
tools headers UAPI: Update linux/fs.h with the kernel sources
mm/pagemap: add documentation of PAGEMAP_SCAN IOCTL
selftests: mm: add pagemap ioctl tests
Peter Xu (1):
userfaultfd: UFFD_FEATURE_WP_ASYNC
Documentation/admin-guide/mm/pagemap.rst | 64 +
Documentation/admin-guide/mm/userfaultfd.rst | 35 +
fs/proc/task_mmu.c | 715 +++++++++
fs/userfaultfd.c | 26 +-
include/linux/hugetlb.h | 1 +
include/linux/userfaultfd_k.h | 21 +-
include/uapi/linux/fs.h | 59 +
include/uapi/linux/userfaultfd.h | 9 +-
mm/hugetlb.c | 34 +-
mm/memory.c | 27 +-
tools/include/uapi/linux/fs.h | 59 +
tools/testing/selftests/mm/.gitignore | 2 +
tools/testing/selftests/mm/Makefile | 3 +-
tools/testing/selftests/mm/config | 1 +
tools/testing/selftests/mm/pagemap_ioctl.c | 1491 ++++++++++++++++++
tools/testing/selftests/mm/run_vmtests.sh | 4 +
16 files changed, 2527 insertions(+), 24 deletions(-)
create mode 100644 tools/testing/selftests/mm/pagemap_ioctl.c
--
2.39.2
[ commit be37bed754ed90b2655382f93f9724b3c1aae847 upstream ]
Dan Carpenter spotted that test_fw_config->reqs will be leaked if
trigger_batched_requests_store() is called two or more times.
The same appears with trigger_batched_requests_async_store().
This bug wasn't triggered by the tests, but observed by Dan's visual
inspection of the code.
The recommended workaround was to return -EBUSY if test_fw_config->reqs
is already allocated.
Fixes: c92316bf8e94 ("test_firmware: add batched firmware tests")
Cc: Luis Chamberlain <mcgrof(a)kernel.org>
Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
Cc: Russ Weight <russell.h.weight(a)intel.com>
Cc: Tianfei Zhang <tianfei.zhang(a)intel.com>
Cc: Shuah Khan <shuah(a)kernel.org>
Cc: Colin Ian King <colin.i.king(a)gmail.com>
Cc: Randy Dunlap <rdunlap(a)infradead.org>
Cc: linux-kselftest(a)vger.kernel.org
Cc: stable(a)vger.kernel.org # v4.14
Suggested-by: Dan Carpenter <error27(a)gmail.com>
Suggested-by: Takashi Iwai <tiwai(a)suse.de>
Link: https://lore.kernel.org/r/20230509084746.48259-2-mirsad.todorovac@alu.unizg…
Signed-off-by: Mirsad Todorovac <mirsad.todorovac(a)alu.unizg.hr>
[ This fix is applied against the 4.14 stable branch. There are no changes to the ]
[ fix in code when compared to the upstread, only the reformatting for backport. ]
---
v2 -> v3:
minor clarifications in the versioning for the patchwork. not change to commit.
v1 -> v2:
removed the Reviewed-by: and Acked-by tags, as this is a slightly different patch and
those need to be reacquired
lib/test_firmware.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/lib/test_firmware.c b/lib/test_firmware.c
index 1c5e5246bf10..5318c5e18acf 100644
--- a/lib/test_firmware.c
+++ b/lib/test_firmware.c
@@ -621,6 +621,11 @@ static ssize_t trigger_batched_requests_store(struct device *dev,
mutex_lock(&test_fw_mutex);
+ if (test_fw_config->reqs) {
+ rc = -EBUSY;
+ goto out_bail;
+ }
+
test_fw_config->reqs = vzalloc(sizeof(struct test_batched_req) *
test_fw_config->num_requests * 2);
if (!test_fw_config->reqs) {
@@ -723,6 +728,11 @@ ssize_t trigger_batched_requests_async_store(struct device *dev,
mutex_lock(&test_fw_mutex);
+ if (test_fw_config->reqs) {
+ rc = -EBUSY;
+ goto out_bail;
+ }
+
test_fw_config->reqs = vzalloc(sizeof(struct test_batched_req) *
test_fw_config->num_requests * 2);
if (!test_fw_config->reqs) {
--
2.34.1
A missing break in kms_tests leads to kselftest hang when the
parameter -s is used.
In current code flow because of missing break in -s, -t parses
args spilled from -s and as -t accepts only valid values as 0,1
so any arg in -s >1 or <0, gets in ksm_test failure
This went undetected since, before the addition of option -t,
the next case -M would immediately break out of the switch
statement but that is no longer the case
Add the missing break statement.
----Before----
./ksm_tests -H -s 100
Invalid merge type
----After----
./ksm_tests -H -s 100
Number of normal pages: 0
Number of huge pages: 50
Total size: 100 MiB
Total time: 0.401732682 s
Average speed: 248.922 MiB/s
Fixes: 07115fcc15b4 ("selftests/mm: add new selftests for KSM")
Signed-off-by: Ayush Jain <ayush.jain3(a)amd.com>
Reviewed-by: David Hildenbrand <david(a)redhat.com>
---
v1 -> v2
collect Reviewed-by from David
Updated Fixes tag from commit 9e7cb94ca218 to 07115fcc15b4
tools/testing/selftests/mm/ksm_tests.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/tools/testing/selftests/mm/ksm_tests.c b/tools/testing/selftests/mm/ksm_tests.c
index 435acebdc325..380b691d3eb9 100644
--- a/tools/testing/selftests/mm/ksm_tests.c
+++ b/tools/testing/selftests/mm/ksm_tests.c
@@ -831,6 +831,7 @@ int main(int argc, char *argv[])
printf("Size must be greater than 0\n");
return KSFT_FAIL;
}
+ break;
case 't':
{
int tmp = atoi(optarg);
--
2.34.1
We want to replace iptables TPROXY with a BPF program at TC ingress.
To make this work in all cases we need to assign a SO_REUSEPORT socket
to an skb, which is currently prohibited. This series adds support for
such sockets to bpf_sk_assing.
I did some refactoring to cut down on the amount of duplicate code. The
key to this is to use INDIRECT_CALL in the reuseport helpers. To show
that this approach is not just beneficial to TC sk_assign I removed
duplicate code for bpf_sk_lookup as well.
Joint work with Daniel Borkmann.
Signed-off-by: Lorenz Bauer <lmb(a)isovalent.com>
---
Changes in v6:
- Reject unhashed UDP sockets in bpf_sk_assign to avoid ref leak
- Link to v5: https://lore.kernel.org/r/20230613-so-reuseport-v5-0-f6686a0dbce0@isovalent…
Changes in v5:
- Drop reuse_sk == sk check in inet[6]_steal_stock (Kuniyuki)
- Link to v4: https://lore.kernel.org/r/20230613-so-reuseport-v4-0-4ece76708bba@isovalent…
Changes in v4:
- WARN_ON_ONCE if reuseport socket is refcounted (Kuniyuki)
- Use inet[6]_ehashfn_t to shorten function declarations (Kuniyuki)
- Shuffle documentation patch around (Kuniyuki)
- Update commit message to explain why IPv6 needs EXPORT_SYMBOL
- Link to v3: https://lore.kernel.org/r/20230613-so-reuseport-v3-0-907b4cbb7b99@isovalent…
Changes in v3:
- Fix warning re udp_ehashfn and udp6_ehashfn (Simon)
- Return higher scoring connected UDP reuseport sockets (Kuniyuki)
- Fix ipv6 module builds
- Link to v2: https://lore.kernel.org/r/20230613-so-reuseport-v2-0-b7c69a342613@isovalent…
Changes in v2:
- Correct commit abbrev length (Kuniyuki)
- Reduce duplication (Kuniyuki)
- Add checks on sk_state (Martin)
- Split exporting inet[6]_lookup_reuseport into separate patch (Eric)
---
Daniel Borkmann (1):
selftests/bpf: Test that SO_REUSEPORT can be used with sk_assign helper
Lorenz Bauer (7):
udp: re-score reuseport groups when connected sockets are present
bpf: reject unhashed sockets in bpf_sk_assign
net: export inet_lookup_reuseport and inet6_lookup_reuseport
net: remove duplicate reuseport_lookup functions
net: document inet[6]_lookup_reuseport sk_state requirements
net: remove duplicate sk_lookup helpers
bpf, net: Support SO_REUSEPORT sockets with bpf_sk_assign
include/net/inet6_hashtables.h | 81 ++++++++-
include/net/inet_hashtables.h | 74 +++++++-
include/net/sock.h | 7 +-
include/uapi/linux/bpf.h | 3 -
net/core/filter.c | 4 +-
net/ipv4/inet_hashtables.c | 68 ++++---
net/ipv4/udp.c | 88 ++++-----
net/ipv6/inet6_hashtables.c | 71 +++++---
net/ipv6/udp.c | 98 ++++------
tools/include/uapi/linux/bpf.h | 3 -
tools/testing/selftests/bpf/network_helpers.c | 3 +
.../selftests/bpf/prog_tests/assign_reuse.c | 197 +++++++++++++++++++++
.../selftests/bpf/progs/test_assign_reuse.c | 142 +++++++++++++++
13 files changed, 660 insertions(+), 179 deletions(-)
---
base-commit: 6f5a630d7c57cd79b1f526a95e757311e32d41e5
change-id: 20230613-so-reuseport-e92c526173ee
Best regards,
--
Lorenz Bauer <lmb(a)isovalent.com>