April 2018 - Linux-stable-mirror

by Mauro Carvalho Chehab

Hi Greg, There are two important v4l2-core fixes on the patches merged this week by Linux. 1) media: v4l2-core: fix size of devnode_nums[] bitarray This patch correct a regression against Kernel 4.16. It affects notebooks with advanced Synaptics mice (and similar touch devices). On those devices, the pad produces an image with is handled via V4L2. Without this patch, the input driver OOPSes at probing time: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?… 2) v4l2-compat-ioctl32: don't oops on overlay This patch complements the security fix we've made at the V4L2 core compat32 logic. It fixes an illegal use of an __user pointer without first convert into a Kernel pointer with get_user(). It wasn't detect before, as it uses an obscure streaming mode of V4L2 (overlay mode): https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?… This one should go all the way down to stable Kernels. Here, I was able to reproduce the bug with both upstream Kernel and Kernel 3.18. The patch applied without any conflicts on both. Could you please add both on your next set of -stable releases? Thanks, Mauro

6 years, 9 months

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[PATCH] Sparc

by David Miller

Please queue up the attached sparc bug fix for 4.16 -stable. Thank you.

6 years, 9 months

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[PATCHES] Networking

by David Miller

Please queue up the following networking bug fixes for v4.4 and v4.16 -stable, respectively. Note, you may wish to take patch "vhost: fix vhost_vq_access_ok() log check" (upsteam d14d2b78090c7de0557362b26a4ca591aa6a9faa) for v4.15 as well because the change it is fixing went into v4.15.17 Thanks!

6 years, 9 months

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[PATCH] Revert "xhci: plat: Register shutdown for xhci_plat"

by Greg Hackmann

Pixel 2 field testers reported that when they tried to reboot their phones with some USB devices plugged in, the reboot would get wedged and eventually trigger watchdog reset. Once the Pixel kernel team found a reliable repro case, they narrowed it down to this commit's 4.4.y backport. Reverting the change made the issue go away. This reverts commit b07c12517f2aed0add8ce18146bb426b14099392. Cc: stable(a)vger.kernel.org Signed-off-by: Greg Hackmann <ghackmann(a)google.com> --- drivers/usb/host/xhci-plat.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c index df327dcc2bac..ea089fdda611 100644 --- a/drivers/usb/host/xhci-plat.c +++ b/drivers/usb/host/xhci-plat.c @@ -420,7 +420,6 @@ MODULE_DEVICE_TABLE(acpi, usb_xhci_acpi_match); static struct platform_driver usb_xhci_driver = { .probe = xhci_plat_probe, .remove = xhci_plat_remove, - .shutdown = usb_hcd_platform_shutdown, .driver = { .name = "xhci-hcd", .pm = &xhci_plat_pm_ops, -- 2.17.0.484.g0c8726318c-goog

6 years, 9 months

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[PATCH v5] blk-mq: Avoid that a completion can be ignored for BLK_EH_RESET_TIMER

by Bart Van Assche

The blk-mq timeout handling code ignores completions that occur after blk_mq_check_expired() has been called and before blk_mq_rq_timed_out() has reset rq->aborted_gstate. If a block driver timeout handler always returns BLK_EH_RESET_TIMER then the result will be that the request never terminates. Since the request state can be updated from two different contexts, namely regular completion and request timeout, this race cannot be fixed with RCU synchronization only. Fix this race as follows: - Use the deadline instead of the request generation to detect whether or not a request timer fired after reinitialization of a request. - Store the request state in the lowest two bits of the deadline instead of the lowest two bits of 'gstate'. - Rename MQ_RQ_STATE_MASK into RQ_STATE_MASK and change it from an enumeration member into a #define such that its type can be changed into unsigned long. That allows to write & ~RQ_STATE_MASK instead of ~(unsigned long)RQ_STATE_MASK. - Remove all request member variables that became superfluous due to this change: gstate, aborted_gstate, gstate_seq and aborted_gstate_sync. - Remove the request state information that became superfluous due to this patch, namely RQF_MQ_TIMEOUT_EXPIRED. - Remove the hctx member that became superfluous due to these changes, namely nr_expired. - Remove the code that became superfluous due to this change, namely the RCU lock and unlock statements in blk_mq_complete_request() and also the synchronize_rcu() call in the timeout handler. Signed-off-by: Bart Van Assche <bart.vanassche(a)wdc.com> Cc: Tejun Heo <tj(a)kernel.org> Cc: Christoph Hellwig <hch(a)lst.de> Cc: Ming Lei <ming.lei(a)redhat.com> Cc: Sagi Grimberg <sagi(a)grimberg.me> Cc: Israel Rukshin <israelr(a)mellanox.com>, Cc: Max Gurtovoy <maxg(a)mellanox.com> Cc: <stable(a)vger.kernel.org> # v4.16 --- Changes compared to v4: - Addressed multiple review comments from Christoph. The most important are that atomic_long_cmpxchg() has been changed into cmpxchg() and also that there is now a nice and clean split between the legacy and blk-mq versions of blk_add_timer(). - Changed the patch name and modified the patch description because there is disagreement about whether or not the v4.16 blk-mq core can complete a single request twice. Kept the "Cc: stable" tag because of https://bugzilla.kernel.org/show_bug.cgi?id=199077. Changes compared to v3 (see also https://www.mail-archive.com/linux-block@vger.kernel.org/msg20073.html): - Removed the spinlock again that was introduced to protect the request state. v4 uses atomic_long_cmpxchg() instead. - Split __deadline into two variables - one for the legacy block layer and one for blk-mq. Changes compared to v2 (https://www.mail-archive.com/linux-block@vger.kernel.org/msg18338.html): - Rebased and retested on top of kernel v4.16. Changes compared to v1 (https://www.mail-archive.com/linux-block@vger.kernel.org/msg18089.html): - Removed the gstate and aborted_gstate members of struct request and used the __deadline member to encode both the generation and state information. block/blk-core.c | 2 - block/blk-mq-debugfs.c | 1 - block/blk-mq.c | 174 +++++-------------------------------------------- block/blk-mq.h | 65 ++++++++++-------- block/blk-timeout.c | 89 ++++++++++++++----------- block/blk.h | 13 ++-- include/linux/blk-mq.h | 1 - include/linux/blkdev.h | 30 ++------- 8 files changed, 118 insertions(+), 257 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 8625ec929fe5..181b1a688a5b 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -200,8 +200,6 @@ void blk_rq_init(struct request_queue *q, struct request *rq) rq->start_time = jiffies; set_start_time_ns(rq); rq->part = NULL; - seqcount_init(&rq->gstate_seq); - u64_stats_init(&rq->aborted_gstate_sync); } EXPORT_SYMBOL(blk_rq_init); diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c index 6f72413b6cab..80c7c585769f 100644 --- a/block/blk-mq-debugfs.c +++ b/block/blk-mq-debugfs.c @@ -345,7 +345,6 @@ static const char *const rqf_name[] = { RQF_NAME(STATS), RQF_NAME(SPECIAL_PAYLOAD), RQF_NAME(ZONE_WRITE_LOCKED), - RQF_NAME(MQ_TIMEOUT_EXPIRED), RQF_NAME(MQ_POLL_SLEPT), }; #undef RQF_NAME diff --git a/block/blk-mq.c b/block/blk-mq.c index 7816d28b7219..0680977d6d98 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -305,7 +305,6 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data, rq->special = NULL; /* tag was already set */ rq->extra_len = 0; - rq->__deadline = 0; INIT_LIST_HEAD(&rq->timeout_list); rq->timeout = 0; @@ -481,7 +480,8 @@ void blk_mq_free_request(struct request *rq) if (blk_rq_rl(rq)) blk_put_rl(blk_rq_rl(rq)); - blk_mq_rq_update_state(rq, MQ_RQ_IDLE); + if (!blk_mq_change_rq_state(rq, blk_mq_rq_state(rq), MQ_RQ_IDLE)) + WARN_ON_ONCE(true); if (rq->tag != -1) blk_mq_put_tag(hctx, hctx->tags, ctx, rq->tag); if (sched_tag != -1) @@ -527,8 +527,7 @@ static void __blk_mq_complete_request(struct request *rq) bool shared = false; int cpu; - WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IN_FLIGHT); - blk_mq_rq_update_state(rq, MQ_RQ_COMPLETE); + WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_COMPLETE); if (rq->internal_tag != -1) blk_mq_sched_completed_request(rq); @@ -577,36 +576,6 @@ static void hctx_lock(struct blk_mq_hw_ctx *hctx, int *srcu_idx) *srcu_idx = srcu_read_lock(hctx->srcu); } -static void blk_mq_rq_update_aborted_gstate(struct request *rq, u64 gstate) -{ - unsigned long flags; - - /* - * blk_mq_rq_aborted_gstate() is used from the completion path and - * can thus be called from irq context. u64_stats_fetch in the - * middle of update on the same CPU leads to lockup. Disable irq - * while updating. - */ - local_irq_save(flags); - u64_stats_update_begin(&rq->aborted_gstate_sync); - rq->aborted_gstate = gstate; - u64_stats_update_end(&rq->aborted_gstate_sync); - local_irq_restore(flags); -} - -static u64 blk_mq_rq_aborted_gstate(struct request *rq) -{ - unsigned int start; - u64 aborted_gstate; - - do { - start = u64_stats_fetch_begin(&rq->aborted_gstate_sync); - aborted_gstate = rq->aborted_gstate; - } while (u64_stats_fetch_retry(&rq->aborted_gstate_sync, start)); - - return aborted_gstate; -} - /** * blk_mq_complete_request - end I/O on a request * @rq: the request being processed @@ -618,27 +587,12 @@ static u64 blk_mq_rq_aborted_gstate(struct request *rq) void blk_mq_complete_request(struct request *rq) { struct request_queue *q = rq->q; - struct blk_mq_hw_ctx *hctx = blk_mq_map_queue(q, rq->mq_ctx->cpu); - int srcu_idx; if (unlikely(blk_should_fake_timeout(q))) return; - /* - * If @rq->aborted_gstate equals the current instance, timeout is - * claiming @rq and we lost. This is synchronized through - * hctx_lock(). See blk_mq_timeout_work() for details. - * - * Completion path never blocks and we can directly use RCU here - * instead of hctx_lock() which can be either RCU or SRCU. - * However, that would complicate paths which want to synchronize - * against us. Let stay in sync with the issue path so that - * hctx_lock() covers both issue and completion paths. - */ - hctx_lock(hctx, &srcu_idx); - if (blk_mq_rq_aborted_gstate(rq) != rq->gstate) + if (blk_mq_change_rq_state(rq, MQ_RQ_IN_FLIGHT, MQ_RQ_COMPLETE)) __blk_mq_complete_request(rq); - hctx_unlock(hctx, srcu_idx); } EXPORT_SYMBOL(blk_mq_complete_request); @@ -662,27 +616,7 @@ void blk_mq_start_request(struct request *rq) wbt_issue(q->rq_wb, &rq->issue_stat); } - WARN_ON_ONCE(blk_mq_rq_state(rq) != MQ_RQ_IDLE); - - /* - * Mark @rq in-flight which also advances the generation number, - * and register for timeout. Protect with a seqcount to allow the - * timeout path to read both @rq->gstate and @rq->deadline - * coherently. - * - * This is the only place where a request is marked in-flight. If - * the timeout path reads an in-flight @rq->gstate, the - * @rq->deadline it reads together under @rq->gstate_seq is - * guaranteed to be the matching one. - */ - preempt_disable(); - write_seqcount_begin(&rq->gstate_seq); - - blk_mq_rq_update_state(rq, MQ_RQ_IN_FLIGHT); - blk_add_timer(rq); - - write_seqcount_end(&rq->gstate_seq); - preempt_enable(); + blk_mq_add_timer(rq, MQ_RQ_IDLE, MQ_RQ_IN_FLIGHT); if (q->dma_drain_size && blk_rq_bytes(rq)) { /* @@ -695,22 +629,19 @@ void blk_mq_start_request(struct request *rq) } EXPORT_SYMBOL(blk_mq_start_request); -/* - * When we reach here because queue is busy, it's safe to change the state - * to IDLE without checking @rq->aborted_gstate because we should still be - * holding the RCU read lock and thus protected against timeout. - */ static void __blk_mq_requeue_request(struct request *rq) { struct request_queue *q = rq->q; + enum mq_rq_state old_state = blk_mq_rq_state(rq); blk_mq_put_driver_tag(rq); trace_block_rq_requeue(q, rq); wbt_requeue(q->rq_wb, &rq->issue_stat); - if (blk_mq_rq_state(rq) != MQ_RQ_IDLE) { - blk_mq_rq_update_state(rq, MQ_RQ_IDLE); + if (old_state != MQ_RQ_IDLE) { + if (!blk_mq_change_rq_state(rq, old_state, MQ_RQ_IDLE)) + WARN_ON_ONCE(true); if (q->dma_drain_size && blk_rq_bytes(rq)) rq->nr_phys_segments--; } @@ -811,7 +742,6 @@ EXPORT_SYMBOL(blk_mq_tag_to_rq); struct blk_mq_timeout_data { unsigned long next; unsigned int next_set; - unsigned int nr_expired; }; static void blk_mq_rq_timed_out(struct request *req, bool reserved) @@ -819,8 +749,6 @@ static void blk_mq_rq_timed_out(struct request *req, bool reserved) const struct blk_mq_ops *ops = req->q->mq_ops; enum blk_eh_timer_return ret = BLK_EH_RESET_TIMER; - req->rq_flags |= RQF_MQ_TIMEOUT_EXPIRED; - if (ops->timeout) ret = ops->timeout(req, reserved); @@ -829,13 +757,7 @@ static void blk_mq_rq_timed_out(struct request *req, bool reserved) __blk_mq_complete_request(req); break; case BLK_EH_RESET_TIMER: - /* - * As nothing prevents from completion happening while - * ->aborted_gstate is set, this may lead to ignored - * completions and further spurious timeouts. - */ - blk_mq_rq_update_aborted_gstate(req, 0); - blk_add_timer(req); + blk_mq_add_timer(req, MQ_RQ_COMPLETE, MQ_RQ_IN_FLIGHT); break; case BLK_EH_NOT_HANDLED: break; @@ -849,60 +771,23 @@ static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx, struct request *rq, void *priv, bool reserved) { struct blk_mq_timeout_data *data = priv; - unsigned long gstate, deadline; - int start; - - might_sleep(); - - if (rq->rq_flags & RQF_MQ_TIMEOUT_EXPIRED) - return; - - /* read coherent snapshots of @rq->state_gen and @rq->deadline */ - while (true) { - start = read_seqcount_begin(&rq->gstate_seq); - gstate = READ_ONCE(rq->gstate); - deadline = blk_rq_deadline(rq); - if (!read_seqcount_retry(&rq->gstate_seq, start)) - break; - cond_resched(); - } + unsigned long deadline = blk_rq_deadline(rq); - /* if in-flight && overdue, mark for abortion */ - if ((gstate & MQ_RQ_STATE_MASK) == MQ_RQ_IN_FLIGHT && - time_after_eq(jiffies, deadline)) { - blk_mq_rq_update_aborted_gstate(rq, gstate); - data->nr_expired++; - hctx->nr_expired++; + if (time_after_eq(jiffies, deadline) && + blk_mq_change_rq_state(rq, MQ_RQ_IN_FLIGHT, MQ_RQ_COMPLETE)) { + blk_mq_rq_timed_out(rq, reserved); } else if (!data->next_set || time_after(data->next, deadline)) { data->next = deadline; data->next_set = 1; } -} -static void blk_mq_terminate_expired(struct blk_mq_hw_ctx *hctx, - struct request *rq, void *priv, bool reserved) -{ - /* - * We marked @rq->aborted_gstate and waited for RCU. If there were - * completions that we lost to, they would have finished and - * updated @rq->gstate by now; otherwise, the completion path is - * now guaranteed to see @rq->aborted_gstate and yield. If - * @rq->aborted_gstate still matches @rq->gstate, @rq is ours. - */ - if (!(rq->rq_flags & RQF_MQ_TIMEOUT_EXPIRED) && - READ_ONCE(rq->gstate) == rq->aborted_gstate) - blk_mq_rq_timed_out(rq, reserved); } static void blk_mq_timeout_work(struct work_struct *work) { struct request_queue *q = container_of(work, struct request_queue, timeout_work); - struct blk_mq_timeout_data data = { - .next = 0, - .next_set = 0, - .nr_expired = 0, - }; + struct blk_mq_timeout_data data = { }; struct blk_mq_hw_ctx *hctx; int i; @@ -925,33 +810,6 @@ static void blk_mq_timeout_work(struct work_struct *work) /* scan for the expired ones and set their ->aborted_gstate */ blk_mq_queue_tag_busy_iter(q, blk_mq_check_expired, &data); - if (data.nr_expired) { - bool has_rcu = false; - - /* - * Wait till everyone sees ->aborted_gstate. The - * sequential waits for SRCUs aren't ideal. If this ever - * becomes a problem, we can add per-hw_ctx rcu_head and - * wait in parallel. - */ - queue_for_each_hw_ctx(q, hctx, i) { - if (!hctx->nr_expired) - continue; - - if (!(hctx->flags & BLK_MQ_F_BLOCKING)) - has_rcu = true; - else - synchronize_srcu(hctx->srcu); - - hctx->nr_expired = 0; - } - if (has_rcu) - synchronize_rcu(); - - /* terminate the ones we won */ - blk_mq_queue_tag_busy_iter(q, blk_mq_terminate_expired, NULL); - } - if (data.next_set) { data.next = blk_rq_timeout(round_jiffies_up(data.next)); mod_timer(&q->timeout, data.next); @@ -2087,8 +1945,6 @@ static int blk_mq_init_request(struct blk_mq_tag_set *set, struct request *rq, return ret; } - seqcount_init(&rq->gstate_seq); - u64_stats_init(&rq->aborted_gstate_sync); return 0; } diff --git a/block/blk-mq.h b/block/blk-mq.h index 88c558f71819..368cd73a00bd 100644 --- a/block/blk-mq.h +++ b/block/blk-mq.h @@ -27,18 +27,11 @@ struct blk_mq_ctx { struct kobject kobj; } ____cacheline_aligned_in_smp; -/* - * Bits for request->gstate. The lower two bits carry MQ_RQ_* state value - * and the upper bits the generation number. - */ +/* Lowest two bits of request->__deadline. */ enum mq_rq_state { MQ_RQ_IDLE = 0, MQ_RQ_IN_FLIGHT = 1, MQ_RQ_COMPLETE = 2, - - MQ_RQ_STATE_BITS = 2, - MQ_RQ_STATE_MASK = (1 << MQ_RQ_STATE_BITS) - 1, - MQ_RQ_GEN_INC = 1 << MQ_RQ_STATE_BITS, }; void blk_mq_freeze_queue(struct request_queue *q); @@ -100,37 +93,55 @@ extern void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx); void blk_mq_release(struct request_queue *q); +/* + * If the state of request @rq equals @old_state, update deadline and request + * state atomically to @time and @new_state. blk-mq only. + */ +static inline bool blk_mq_rq_set_deadline(struct request *rq, + unsigned long new_time, + enum mq_rq_state old_state, + enum mq_rq_state new_state) +{ + unsigned long old_val, new_val; + + do { + old_val = READ_ONCE(rq->__deadline); + if ((old_val & RQ_STATE_MASK) != old_state) + return false; + new_val = (new_time & ~RQ_STATE_MASK) | + (new_state & RQ_STATE_MASK); + } while (cmpxchg(&rq->__deadline, old_val, new_val) != old_val); + + return true; +} + /** * blk_mq_rq_state() - read the current MQ_RQ_* state of a request * @rq: target request. */ -static inline int blk_mq_rq_state(struct request *rq) +static inline enum mq_rq_state blk_mq_rq_state(struct request *rq) { - return READ_ONCE(rq->gstate) & MQ_RQ_STATE_MASK; + return READ_ONCE(rq->__deadline) & RQ_STATE_MASK; } /** - * blk_mq_rq_update_state() - set the current MQ_RQ_* state of a request - * @rq: target request. - * @state: new state to set. + * blk_mq_change_rq_state - atomically test and set request state + * @rq: Request pointer. + * @old_state: Old request state. + * @new_state: New request state. * - * Set @rq's state to @state. The caller is responsible for ensuring that - * there are no other updaters. A request can transition into IN_FLIGHT - * only from IDLE and doing so increments the generation number. + * Returns %true if and only if the old state was @old and if the state has + * been changed into @new. */ -static inline void blk_mq_rq_update_state(struct request *rq, - enum mq_rq_state state) +static inline bool blk_mq_change_rq_state(struct request *rq, + enum mq_rq_state old_state, + enum mq_rq_state new_state) { - u64 old_val = READ_ONCE(rq->gstate); - u64 new_val = (old_val & ~MQ_RQ_STATE_MASK) | state; - - if (state == MQ_RQ_IN_FLIGHT) { - WARN_ON_ONCE((old_val & MQ_RQ_STATE_MASK) != MQ_RQ_IDLE); - new_val += MQ_RQ_GEN_INC; - } + unsigned long old_val = (READ_ONCE(rq->__deadline) & ~RQ_STATE_MASK) | + old_state; + unsigned long new_val = (old_val & ~RQ_STATE_MASK) | new_state; - /* avoid exposing interim values */ - WRITE_ONCE(rq->gstate, new_val); + return cmpxchg(&rq->__deadline, old_val, new_val) == old_val; } static inline struct blk_mq_ctx *__blk_mq_get_ctx(struct request_queue *q, diff --git a/block/blk-timeout.c b/block/blk-timeout.c index 50a191720055..e98da6db7d4b 100644 --- a/block/blk-timeout.c +++ b/block/blk-timeout.c @@ -165,8 +165,9 @@ void blk_abort_request(struct request *req) * immediately and that scan sees the new timeout value. * No need for fancy synchronizations. */ - blk_rq_set_deadline(req, jiffies); - kblockd_schedule_work(&req->q->timeout_work); + if (blk_mq_rq_set_deadline(req, jiffies, MQ_RQ_IN_FLIGHT, + MQ_RQ_IN_FLIGHT)) + kblockd_schedule_work(&req->q->timeout_work); } else { if (blk_mark_rq_complete(req)) return; @@ -187,52 +188,17 @@ unsigned long blk_rq_timeout(unsigned long timeout) return timeout; } -/** - * blk_add_timer - Start timeout timer for a single request - * @req: request that is about to start running. - * - * Notes: - * Each request has its own timer, and as it is added to the queue, we - * set up the timer. When the request completes, we cancel the timer. - */ -void blk_add_timer(struct request *req) +static void __blk_add_timer(struct request *req) { struct request_queue *q = req->q; unsigned long expiry; - if (!q->mq_ops) - lockdep_assert_held(q->queue_lock); - - /* blk-mq has its own handler, so we don't need ->rq_timed_out_fn */ - if (!q->mq_ops && !q->rq_timed_out_fn) - return; - - BUG_ON(!list_empty(&req->timeout_list)); - - /* - * Some LLDs, like scsi, peek at the timeout to prevent a - * command from being retried forever. - */ - if (!req->timeout) - req->timeout = q->rq_timeout; - - blk_rq_set_deadline(req, jiffies + req->timeout); - req->rq_flags &= ~RQF_MQ_TIMEOUT_EXPIRED; - - /* - * Only the non-mq case needs to add the request to a protected list. - * For the mq case we simply scan the tag map. - */ - if (!q->mq_ops) - list_add_tail(&req->timeout_list, &req->q->timeout_list); - /* * If the timer isn't already pending or this timeout is earlier * than an existing one, modify the timer. Round up to next nearest * second. */ expiry = blk_rq_timeout(round_jiffies_up(blk_rq_deadline(req))); - if (!timer_pending(&q->timeout) || time_before(expiry, q->timeout.expires)) { unsigned long diff = q->timeout.expires - expiry; @@ -247,5 +213,52 @@ void blk_add_timer(struct request *req) if (!timer_pending(&q->timeout) || (diff >= HZ / 2)) mod_timer(&q->timeout, expiry); } +} + +/** + * blk_add_timer - Start timeout timer for a single request + * @req: request that is about to start running. + * + * Notes: + * Each request has its own timer, and as it is added to the queue, we + * set up the timer. When the request completes, we cancel the timer. + */ +void blk_add_timer(struct request *req) +{ + struct request_queue *q = req->q; + + lockdep_assert_held(q->queue_lock); + if (!q->rq_timed_out_fn) + return; + if (!req->timeout) + req->timeout = q->rq_timeout; + + blk_rq_set_deadline(req, jiffies + req->timeout); + list_add_tail(&req->timeout_list, &req->q->timeout_list); + + return __blk_add_timer(req); +} + +/** + * blk_mq_add_timer - set the deadline for a single request + * @req: request for which to set the deadline. + * @old: current request state. + * @new: new request state. + * + * Sets the deadline of a request if and only if it has state @old and + * at the same time changes the request state from @old into @new. The caller + * must guarantee that the request state won't be modified while this function + * is in progress. + */ +void blk_mq_add_timer(struct request *req, enum mq_rq_state old, + enum mq_rq_state new) +{ + struct request_queue *q = req->q; + + if (!req->timeout) + req->timeout = q->rq_timeout; + if (!blk_mq_rq_set_deadline(req, jiffies + req->timeout, old, new)) + WARN_ON_ONCE(true); + return __blk_add_timer(req); } diff --git a/block/blk.h b/block/blk.h index b034fd2460c4..7cd64f533a46 100644 --- a/block/blk.h +++ b/block/blk.h @@ -170,6 +170,8 @@ static inline bool bio_integrity_endio(struct bio *bio) void blk_timeout_work(struct work_struct *work); unsigned long blk_rq_timeout(unsigned long timeout); void blk_add_timer(struct request *req); +void blk_mq_add_timer(struct request *req, enum mq_rq_state old, + enum mq_rq_state new); void blk_delete_timer(struct request *); @@ -308,18 +310,19 @@ static inline void req_set_nomerge(struct request_queue *q, struct request *req) } /* - * Steal a bit from this field for legacy IO path atomic IO marking. Note that - * setting the deadline clears the bottom bit, potentially clearing the - * completed bit. The user has to be OK with this (current ones are fine). + * Steal two bits from this field. The legacy IO path uses the lowest bit for + * atomic IO marking. Note that setting the deadline clears the bottom bit, + * potentially clearing the completed bit. The current legacy block layer is + * fine with that. Must be called with the request queue lock held. */ static inline void blk_rq_set_deadline(struct request *rq, unsigned long time) { - rq->__deadline = time & ~0x1UL; + rq->__deadline = time & RQ_STATE_MASK; } static inline unsigned long blk_rq_deadline(struct request *rq) { - return rq->__deadline & ~0x1UL; + return rq->__deadline & ~RQ_STATE_MASK; } /* diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h index 8efcf49796a3..13ccbb418e89 100644 --- a/include/linux/blk-mq.h +++ b/include/linux/blk-mq.h @@ -51,7 +51,6 @@ struct blk_mq_hw_ctx { unsigned int queue_num; atomic_t nr_active; - unsigned int nr_expired; struct hlist_node cpuhp_dead; struct kobject kobj; diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 6075d1a6760c..302ce237c728 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -27,7 +27,6 @@ #include <linux/percpu-refcount.h> #include <linux/scatterlist.h> #include <linux/blkzoned.h> -#include <linux/seqlock.h> #include <linux/u64_stats_sync.h> struct module; @@ -125,10 +124,8 @@ typedef __u32 __bitwise req_flags_t; #define RQF_SPECIAL_PAYLOAD ((__force req_flags_t)(1 << 18)) /* The per-zone write lock is held for this request */ #define RQF_ZONE_WRITE_LOCKED ((__force req_flags_t)(1 << 19)) -/* timeout is expired */ -#define RQF_MQ_TIMEOUT_EXPIRED ((__force req_flags_t)(1 << 20)) /* already slept for hybrid poll */ -#define RQF_MQ_POLL_SLEPT ((__force req_flags_t)(1 << 21)) +#define RQF_MQ_POLL_SLEPT ((__force req_flags_t)(1 << 20)) /* flags that prevent us from merging requests: */ #define RQF_NOMERGE_FLAGS \ @@ -226,27 +223,12 @@ struct request { unsigned int extra_len; /* length of alignment and padding */ /* - * On blk-mq, the lower bits of ->gstate (generation number and - * state) carry the MQ_RQ_* state value and the upper bits the - * generation number which is monotonically incremented and used to - * distinguish the reuse instances. - * - * ->gstate_seq allows updates to ->gstate and other fields - * (currently ->deadline) during request start to be read - * atomically from the timeout path, so that it can operate on a - * coherent set of information. + * Access through blk_rq_deadline() and blk_rq_set_deadline(), + * blk_mark_rq_complete(), blk_clear_rq_complete() and + * blk_rq_is_complete() for legacy queues or blk_mq_rq_state() for + * blk-mq queues. */ - seqcount_t gstate_seq; - u64 gstate; - - /* - * ->aborted_gstate is used by the timeout to claim a specific - * recycle instance of this request. See blk_mq_timeout_work(). - */ - struct u64_stats_sync aborted_gstate_sync; - u64 aborted_gstate; - - /* access through blk_rq_set_deadline, blk_rq_deadline */ +#define RQ_STATE_MASK 0x3UL unsigned long __deadline; struct list_head timeout_list; -- 2.16.2

6 years, 9 months

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[patch 08/27] mm, slab: reschedule cache_reap() on the same CPU

by akpm＠linux-foundation.org

From: Vlastimil Babka <vbabka(a)suse.cz> Subject: mm, slab: reschedule cache_reap() on the same CPU cache_reap() is initially scheduled in start_cpu_timer() via schedule_delayed_work_on(). But then the next iterations are scheduled via schedule_delayed_work(), i.e. using WORK_CPU_UNBOUND. Thus since commit ef557180447f ("workqueue: schedule WORK_CPU_UNBOUND work on wq_unbound_cpumask CPUs") there is no guarantee the future iterations will run on the originally intended cpu, although it's still preferred. I was able to demonstrate this with /sys/module/workqueue/parameters/debug_force_rr_cpu. IIUC, it may also happen due to migrating timers in nohz context. As a result, some cpu's would be calling cache_reap() more frequently and others never. This patch uses schedule_delayed_work_on() with the current cpu when scheduling the next iteration. Link: http://lkml.kernel.org/r/20180411070007.32225-1-vbabka@suse.cz Fixes: ef557180447f ("workqueue: schedule WORK_CPU_UNBOUND work on wq_unbound_cpumask CPUs") Signed-off-by: Vlastimil Babka <vbabka(a)suse.cz> Acked-by: Pekka Enberg <penberg(a)kernel.org> Acked-by: Christoph Lameter <cl(a)linux.com> Cc: Joonsoo Kim <iamjoonsoo.kim(a)lge.com> Cc: David Rientjes <rientjes(a)google.com> Cc: Tejun Heo <tj(a)kernel.org> Cc: Lai Jiangshan <jiangshanlai(a)gmail.com> Cc: John Stultz <john.stultz(a)linaro.org> Cc: Thomas Gleixner <tglx(a)linutronix.de> Cc: Stephen Boyd <sboyd(a)kernel.org> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/slab.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff -puN mm/slab.c~mm-slab-reschedule-cache_reap-on-the-same-cpu mm/slab.c --- a/mm/slab.c~mm-slab-reschedule-cache_reap-on-the-same-cpu +++ a/mm/slab.c @@ -4086,7 +4086,8 @@ next: next_reap_node(); out: /* Set up the next iteration */ - schedule_delayed_work(work, round_jiffies_relative(REAPTIMEOUT_AC)); + schedule_delayed_work_on(smp_processor_id(), work, + round_jiffies_relative(REAPTIMEOUT_AC)); } void get_slabinfo(struct kmem_cache *cachep, struct slabinfo *sinfo) _

6 years, 9 months

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[patch 06/27] ipc/shm: fix use-after-free of shm file via remap_file_pages()

by akpm＠linux-foundation.org

From: Eric Biggers <ebiggers(a)google.com> Subject: ipc/shm: fix use-after-free of shm file via remap_file_pages() syzbot reported a use-after-free of shm_file_data(file)->file->f_op in shm_get_unmapped_area(), called via sys_remap_file_pages(). Unfortunately it couldn't generate a reproducer, but I found a bug which I think caused it. When remap_file_pages() is passed a full System V shared memory segment, the memory is first unmapped, then a new map is created using the ->vm_file. Between these steps, the shm ID can be removed and reused for a new shm segment. But, shm_mmap() only checks whether the ID is currently valid before calling the underlying file's ->mmap(); it doesn't check whether it was reused. Thus it can use the wrong underlying file, one that was already freed. Fix this by making the "outer" shm file (the one that gets put in ->vm_file) hold a reference to the real shm file, and by making __shm_open() require that the file associated with the shm ID matches the one associated with the "outer" file. Taking the reference to the real shm file is needed to fully solve the problem, since otherwise sfd->file could point to a freed file, which then could be reallocated for the reused shm ID, causing the wrong shm segment to be mapped (and without the required permission checks). Commit 1ac0b6dec656 ("ipc/shm: handle removed segments gracefully in shm_mmap()") almost fixed this bug, but it didn't go far enough because it didn't consider the case where the shm ID is reused. The following program usually reproduces this bug: #include <stdlib.h> #include <sys/shm.h> #include <sys/syscall.h> #include <unistd.h> int main() { int is_parent = (fork() != 0); srand(getpid()); for (;;) { int id = shmget(0xF00F, 4096, IPC_CREAT|0700); if (is_parent) { void *addr = shmat(id, NULL, 0); usleep(rand() % 50); while (!syscall(__NR_remap_file_pages, addr, 4096, 0, 0, 0)); } else { usleep(rand() % 50); shmctl(id, IPC_RMID, NULL); } } } It causes the following NULL pointer dereference due to a 'struct file' being used while it's being freed. (I couldn't actually get a KASAN use-after-free splat like in the syzbot report. But I think it's possible with this bug; it would just take a more extraordinary race...) BUG: unable to handle kernel NULL pointer dereference at 0000000000000058 PGD 0 P4D 0 Oops: 0000 [#1] SMP NOPTI CPU: 9 PID: 258 Comm: syz_ipc Not tainted 4.16.0-05140-gf8cf2f16a7c95 #189 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-20171110_100015-anatol 04/01/2014 RIP: 0010:d_inode include/linux/dcache.h:519 [inline] RIP: 0010:touch_atime+0x25/0xd0 fs/inode.c:1724 [...] Call Trace: file_accessed include/linux/fs.h:2063 [inline] shmem_mmap+0x25/0x40 mm/shmem.c:2149 call_mmap include/linux/fs.h:1789 [inline] shm_mmap+0x34/0x80 ipc/shm.c:465 call_mmap include/linux/fs.h:1789 [inline] mmap_region+0x309/0x5b0 mm/mmap.c:1712 do_mmap+0x294/0x4a0 mm/mmap.c:1483 do_mmap_pgoff include/linux/mm.h:2235 [inline] SYSC_remap_file_pages mm/mmap.c:2853 [inline] SyS_remap_file_pages+0x232/0x310 mm/mmap.c:2769 do_syscall_64+0x64/0x1a0 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 [ebiggers(a)google.com: add comment] Link: http://lkml.kernel.org/r/20180410192850.235835-1-ebiggers3@gmail.com Link: http://lkml.kernel.org/r/20180409043039.28915-1-ebiggers3@gmail.com Reported-by: syzbot+d11f321e7f1923157eac80aa990b446596f46439(a)syzkaller.appspotmail.com Fixes: c8d78c1823f4 ("mm: replace remap_file_pages() syscall with emulation") Signed-off-by: Eric Biggers <ebiggers(a)google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov(a)linux.intel.com> Acked-by: Davidlohr Bueso <dbueso(a)suse.de> Cc: Manfred Spraul <manfred(a)colorfullife.com> Cc: "Eric W . Biederman" <ebiederm(a)xmission.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- ipc/shm.c | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-) diff -puN ipc/shm.c~ipc-shm-fix-use-after-free-of-shm-file-via-remap_file_pages ipc/shm.c --- a/ipc/shm.c~ipc-shm-fix-use-after-free-of-shm-file-via-remap_file_pages +++ a/ipc/shm.c @@ -225,6 +225,12 @@ static int __shm_open(struct vm_area_str if (IS_ERR(shp)) return PTR_ERR(shp); + if (shp->shm_file != sfd->file) { + /* ID was reused */ + shm_unlock(shp); + return -EINVAL; + } + shp->shm_atim = ktime_get_real_seconds(); ipc_update_pid(&shp->shm_lprid, task_tgid(current)); shp->shm_nattch++; @@ -455,8 +461,9 @@ static int shm_mmap(struct file *file, s int ret; /* - * In case of remap_file_pages() emulation, the file can represent - * removed IPC ID: propogate shm_lock() error to caller. + * In case of remap_file_pages() emulation, the file can represent an + * IPC ID that was removed, and possibly even reused by another shm + * segment already. Propagate this case as an error to caller. */ ret = __shm_open(vma); if (ret) @@ -480,6 +487,7 @@ static int shm_release(struct inode *ino struct shm_file_data *sfd = shm_file_data(file); put_ipc_ns(sfd->ns); + fput(sfd->file); shm_file_data(file) = NULL; kfree(sfd); return 0; @@ -1445,7 +1453,16 @@ long do_shmat(int shmid, char __user *sh file->f_mapping = shp->shm_file->f_mapping; sfd->id = shp->shm_perm.id; sfd->ns = get_ipc_ns(ns); - sfd->file = shp->shm_file; + /* + * We need to take a reference to the real shm file to prevent the + * pointer from becoming stale in cases where the lifetime of the outer + * file extends beyond that of the shm segment. It's not usually + * possible, but it can happen during remap_file_pages() emulation as + * that unmaps the memory, then does ->mmap() via file reference only. + * We'll deny the ->mmap() if the shm segment was since removed, but to + * detect shm ID reuse we need to compare the file pointers. + */ + sfd->file = get_file(shp->shm_file); sfd->vm_ops = NULL; err = security_mmap_file(file, prot, flags); _

6 years, 9 months

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[patch 03/27] get_user_pages_fast(): return -EFAULT on access_ok failure

by akpm＠linux-foundation.org

From: "Michael S. Tsirkin" <mst(a)redhat.com> Subject: get_user_pages_fast(): return -EFAULT on access_ok failure get_user_pages_fast is supposed to be a faster drop-in equivalent of get_user_pages. As such, callers expect it to return a negative return code when passed an invalid address, and never expect it to return 0 when passed a positive number of pages, since its documentation says: * Returns number of pages pinned. This may be fewer than the number * requested. If nr_pages is 0 or negative, returns 0. If no pages * were pinned, returns -errno. When get_user_pages_fast fall back on get_user_pages this is exactly what happens. Unfortunately the implementation is inconsistent: it returns 0 if passed a kernel address, confusing callers: for example, the following is pretty common but does not appear to do the right thing with a kernel address: ret = get_user_pages_fast(addr, 1, writeable, &page); if (ret < 0) return ret; Change get_user_pages_fast to return -EFAULT when supplied a kernel address to make it match expectations. All callers have been audited for consistency with the documented semantics. Link: http://lkml.kernel.org/r/1522962072-182137-4-git-send-email-mst@redhat.com Fixes: 5b65c4677a57 ("mm, x86/mm: Fix performance regression in get_user_pages_fast()") Signed-off-by: Michael S. Tsirkin <mst(a)redhat.com> Reported-by: syzbot+6304bf97ef436580fede(a)syzkaller.appspotmail.com Reviewed-by: Andrew Morton <akpm(a)linux-foundation.org> Cc: Kirill A. Shutemov <kirill.shutemov(a)linux.intel.com> Cc: Huang Ying <ying.huang(a)intel.com> Cc: Jonathan Corbet <corbet(a)lwn.net> Cc: Peter Zijlstra <peterz(a)infradead.org> Cc: Thomas Gleixner <tglx(a)linutronix.de> Cc: Thorsten Leemhuis <regressions(a)leemhuis.info> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/gup.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff -puN mm/gup.c~gup-return-efault-on-access_ok-failure mm/gup.c --- a/mm/gup.c~gup-return-efault-on-access_ok-failure +++ a/mm/gup.c @@ -1806,9 +1806,12 @@ int get_user_pages_fast(unsigned long st len = (unsigned long) nr_pages << PAGE_SHIFT; end = start + len; + if (nr_pages <= 0) + return 0; + if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ, (void __user *)start, len))) - return 0; + return -EFAULT; if (gup_fast_permitted(start, nr_pages, write)) { local_irq_disable(); _

6 years, 9 months

1
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[patch 02/27] mm/gup_benchmark: handle gup failures

by akpm＠linux-foundation.org

From: "Michael S. Tsirkin" <mst(a)redhat.com> Subject: mm/gup_benchmark: handle gup failures Patch series "mm/get_user_pages_fast fixes, cleanups", v2. Turns out get_user_pages_fast and __get_user_pages_fast return different values on error when given a single page: __get_user_pages_fast returns 0. get_user_pages_fast returns either 0 or an error. Callers of get_user_pages_fast expect an error so fix it up to return an error consistently. Stress the difference between get_user_pages_fast and __get_user_pages_fast to make sure callers aren't confused. This patch (of 3): __gup_benchmark_ioctl does not handle the case where get_user_pages_fast fails: - a negative return code will cause a buffer overrun - returning with partial success will cause use of uninitialized memory. [akpm(a)linux-foundation.org: simplification] Link: http://lkml.kernel.org/r/1522962072-182137-3-git-send-email-mst@redhat.com Signed-off-by: Michael S. Tsirkin <mst(a)redhat.com> Reviewed-by: Andrew Morton <akpm(a)linux-foundation.org> Cc: Kirill A. Shutemov <kirill.shutemov(a)linux.intel.com> Cc: Huang Ying <ying.huang(a)intel.com> Cc: Jonathan Corbet <corbet(a)lwn.net> Cc: Linus Torvalds <torvalds(a)linux-foundation.org> Cc: Peter Zijlstra <peterz(a)infradead.org> Cc: Thomas Gleixner <tglx(a)linutronix.de> Cc: Thorsten Leemhuis <regressions(a)leemhuis.info> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/gup_benchmark.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff -puN mm/gup_benchmark.c~mm-gup_benchmark-handle-gup-failures mm/gup_benchmark.c --- a/mm/gup_benchmark.c~mm-gup_benchmark-handle-gup-failures +++ a/mm/gup_benchmark.c @@ -23,7 +23,7 @@ static int __gup_benchmark_ioctl(unsigne struct page **pages; nr_pages = gup->size / PAGE_SIZE; - pages = kvmalloc(sizeof(void *) * nr_pages, GFP_KERNEL); + pages = kvzalloc(sizeof(void *) * nr_pages, GFP_KERNEL); if (!pages) return -ENOMEM; @@ -41,6 +41,8 @@ static int __gup_benchmark_ioctl(unsigne } nr = get_user_pages_fast(addr, nr, gup->flags & 1, pages + i); + if (nr <= 0) + break; i += nr; } end_time = ktime_get(); _

6 years, 9 months

1
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[patch 01/27] resource: fix integer overflow at reallocation

by akpm＠linux-foundation.org

From: Takashi Iwai <tiwai(a)suse.de> Subject: resource: fix integer overflow at reallocation We've got a bug report indicating a kernel panic at booting on an x86-32 system, and it turned out to be the invalid PCI resource assigned after reallocation. __find_resource() first aligns the resource start address and resets the end address with start+size-1 accordingly, then checks whether it's contained. Here the end address may overflow the integer, although resource_contains() still returns true because the function validates only start and end address. So this ends up with returning an invalid resource (start > end). There was already an attempt to cover such a problem in the commit 47ea91b4052d ("Resource: fix wrong resource window calculation"), but this case is an overseen one. This patch adds the validity check of the newly calculated resource for avoiding the integer overflow problem. Bugzilla: http://bugzilla.opensuse.org/show_bug.cgi?id=1086739 Link: http://lkml.kernel.org/r/s5hpo37d5l8.wl-tiwai@suse.de Fixes: 23c570a67448 ("resource: ability to resize an allocated resource") Signed-off-by: Takashi Iwai <tiwai(a)suse.de> Reported-by: Michael Henders <hendersm(a)shaw.ca> Tested-by: Michael Henders <hendersm(a)shaw.ca> Reviewed-by: Andrew Morton <akpm(a)linux-foundation.org> Cc: Ram Pai <linuxram(a)us.ibm.com> Cc: Bjorn Helgaas <bhelgaas(a)google.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- kernel/resource.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff -puN kernel/resource.c~resource-fix-integer-overflow-at-reallocation-v1 kernel/resource.c --- a/kernel/resource.c~resource-fix-integer-overflow-at-reallocation-v1 +++ a/kernel/resource.c @@ -651,7 +651,8 @@ static int __find_resource(struct resour alloc.start = constraint->alignf(constraint->alignf_data, &avail, size, constraint->align); alloc.end = alloc.start + size - 1; - if (resource_contains(&avail, &alloc)) { + if (alloc.start <= alloc.end && + resource_contains(&avail, &alloc)) { new->start = alloc.start; new->end = alloc.end; return 0; _

6 years, 9 months

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