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20b2e3029e
lockdep report following warning in test: [25176.843958] ================================= [25176.844519] [ INFO: inconsistent lock state ] [25176.845047] 4.1.0-rc3 #22 Tainted: G W [25176.845591] --------------------------------- [25176.846153] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. [25176.846713] fsstress/26661 [HC0[0]:SC1[1]:HE1:SE0] takes: [25176.847246] (&wr_ctx->wr_lock){+.?...}, at: [<ffffffffa04cdc6d>] scrub_free_ctx+0x2d/0xf0 [btrfs] [25176.847838] {SOFTIRQ-ON-W} state was registered at: [25176.848396] [<ffffffff810bf460>] __lock_acquire+0x6a0/0xe10 [25176.848955] [<ffffffff810bfd1e>] lock_acquire+0xce/0x2c0 [25176.849491] [<ffffffff816489af>] mutex_lock_nested+0x7f/0x410 [25176.850029] [<ffffffffa04d04ff>] scrub_stripe+0x4df/0x1080 [btrfs] [25176.850575] [<ffffffffa04d11b1>] scrub_chunk.isra.19+0x111/0x130 [btrfs] [25176.851110] [<ffffffffa04d144c>] scrub_enumerate_chunks+0x27c/0x510 [btrfs] [25176.851660] [<ffffffffa04d3b87>] btrfs_scrub_dev+0x1c7/0x6c0 [btrfs] [25176.852189] [<ffffffffa04e918e>] btrfs_dev_replace_start+0x36e/0x450 [btrfs] [25176.852771] [<ffffffffa04a98e0>] btrfs_ioctl+0x1e10/0x2d20 [btrfs] [25176.853315] [<ffffffff8121c5b8>] do_vfs_ioctl+0x318/0x570 [25176.853868] [<ffffffff8121c851>] SyS_ioctl+0x41/0x80 [25176.854406] [<ffffffff8164da17>] system_call_fastpath+0x12/0x6f [25176.854935] irq event stamp: 51506 [25176.855511] hardirqs last enabled at (51506): [<ffffffff810d4ce5>] vprintk_emit+0x225/0x5e0 [25176.856059] hardirqs last disabled at (51505): [<ffffffff810d4b77>] vprintk_emit+0xb7/0x5e0 [25176.856642] softirqs last enabled at (50886): [<ffffffff81067a23>] __do_softirq+0x363/0x640 [25176.857184] softirqs last disabled at (50949): [<ffffffff8106804d>] irq_exit+0x10d/0x120 [25176.857746] other info that might help us debug this: [25176.858845] Possible unsafe locking scenario: [25176.859981] CPU0 [25176.860537] ---- [25176.861059] lock(&wr_ctx->wr_lock); [25176.861705] <Interrupt> [25176.862272] lock(&wr_ctx->wr_lock); [25176.862881] *** DEADLOCK *** Reason: Above warning is caused by: Interrupt -> bio_endio() -> ... -> scrub_put_ctx() -> scrub_free_ctx() *1 -> ... -> mutex_lock(&wr_ctx->wr_lock); scrub_put_ctx() is allowed to be called in end_bio interrupt, but in code design, it will never call scrub_free_ctx(sctx) in interrupe context(above *1), because btrfs_scrub_dev() get one additional reference of sctx->refs, which makes scrub_free_ctx() only called withine btrfs_scrub_dev(). Now the code runs out of our wish, because free sequence in scrub_pending_bio_dec() have a gap. Current code: -----------------------------------+----------------------------------- scrub_pending_bio_dec() | btrfs_scrub_dev -----------------------------------+----------------------------------- atomic_dec(&sctx->bios_in_flight); | wake_up(&sctx->list_wait); | | scrub_put_ctx() | -> atomic_dec_and_test(&sctx->refs) scrub_put_ctx(sctx); | -> atomic_dec_and_test(&sctx->refs)| -> scrub_free_ctx() | -----------------------------------+----------------------------------- We expected: -----------------------------------+----------------------------------- scrub_pending_bio_dec() | btrfs_scrub_dev -----------------------------------+----------------------------------- atomic_dec(&sctx->bios_in_flight); | wake_up(&sctx->list_wait); | scrub_put_ctx(sctx); | -> atomic_dec_and_test(&sctx->refs)| | scrub_put_ctx() | -> atomic_dec_and_test(&sctx->refs) | -> scrub_free_ctx() -----------------------------------+----------------------------------- Fix: Move scrub_pending_bio_dec() to a workqueue, to avoid this function run in interrupt context. Tested by check tracelog in debug. Changelog v1->v2: Use workqueue instead of adjust function call sequence in v1, because v1 will introduce a bug pointed out by: Filipe David Manana <fdmanana@gmail.com> Reported-by: Qu Wenruo <quwenruo@cn.fujitsu.com> Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com> Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Chris Mason <clm@fb.com>
84 lines
2.9 KiB
C
84 lines
2.9 KiB
C
/*
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* Copyright (C) 2007 Oracle. All rights reserved.
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* Copyright (C) 2014 Fujitsu. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#ifndef __BTRFS_ASYNC_THREAD_
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#define __BTRFS_ASYNC_THREAD_
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#include <linux/workqueue.h>
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struct btrfs_workqueue;
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/* Internal use only */
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struct __btrfs_workqueue;
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struct btrfs_work;
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typedef void (*btrfs_func_t)(struct btrfs_work *arg);
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typedef void (*btrfs_work_func_t)(struct work_struct *arg);
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struct btrfs_work {
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btrfs_func_t func;
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btrfs_func_t ordered_func;
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btrfs_func_t ordered_free;
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/* Don't touch things below */
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struct work_struct normal_work;
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struct list_head ordered_list;
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struct __btrfs_workqueue *wq;
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unsigned long flags;
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};
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#define BTRFS_WORK_HELPER_PROTO(name) \
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void btrfs_##name(struct work_struct *arg)
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BTRFS_WORK_HELPER_PROTO(worker_helper);
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BTRFS_WORK_HELPER_PROTO(delalloc_helper);
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BTRFS_WORK_HELPER_PROTO(flush_delalloc_helper);
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BTRFS_WORK_HELPER_PROTO(cache_helper);
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BTRFS_WORK_HELPER_PROTO(submit_helper);
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BTRFS_WORK_HELPER_PROTO(fixup_helper);
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BTRFS_WORK_HELPER_PROTO(endio_helper);
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BTRFS_WORK_HELPER_PROTO(endio_meta_helper);
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BTRFS_WORK_HELPER_PROTO(endio_meta_write_helper);
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BTRFS_WORK_HELPER_PROTO(endio_raid56_helper);
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BTRFS_WORK_HELPER_PROTO(endio_repair_helper);
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BTRFS_WORK_HELPER_PROTO(rmw_helper);
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BTRFS_WORK_HELPER_PROTO(endio_write_helper);
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BTRFS_WORK_HELPER_PROTO(freespace_write_helper);
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BTRFS_WORK_HELPER_PROTO(delayed_meta_helper);
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BTRFS_WORK_HELPER_PROTO(readahead_helper);
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BTRFS_WORK_HELPER_PROTO(qgroup_rescan_helper);
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BTRFS_WORK_HELPER_PROTO(extent_refs_helper);
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BTRFS_WORK_HELPER_PROTO(scrub_helper);
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BTRFS_WORK_HELPER_PROTO(scrubwrc_helper);
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BTRFS_WORK_HELPER_PROTO(scrubnc_helper);
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BTRFS_WORK_HELPER_PROTO(scrubparity_helper);
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struct btrfs_workqueue *btrfs_alloc_workqueue(const char *name,
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unsigned int flags,
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int max_active,
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int thresh);
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void btrfs_init_work(struct btrfs_work *work, btrfs_work_func_t helper,
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btrfs_func_t func,
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btrfs_func_t ordered_func,
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btrfs_func_t ordered_free);
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void btrfs_queue_work(struct btrfs_workqueue *wq,
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struct btrfs_work *work);
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void btrfs_destroy_workqueue(struct btrfs_workqueue *wq);
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void btrfs_workqueue_set_max(struct btrfs_workqueue *wq, int max);
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void btrfs_set_work_high_priority(struct btrfs_work *work);
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#endif
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