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866e98a4d9
Running delayed iputs, which never happens in an irq context, needs to
lock the spinlock fs_info->delayed_iput_lock. When finishing bios for
data writes (irq context, bio.c) we call btrfs_put_ordered_extent() which
needs to add a delayed iput and for that it needs to acquire the spinlock
fs_info->delayed_iput_lock. Without disabling irqs when running delayed
iputs we can therefore deadlock on that spinlock. The same deadlock can
also happen when adding an inode to the delayed iputs list, since this
can be done outside an irq context as well.
Syzbot recently reported this, which results in the following trace:
================================
WARNING: inconsistent lock state
6.4.0-syzkaller-09904-ga507db1d8fdc #0 Not tainted
--------------------------------
inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage.
btrfs-cleaner/16079 [HC0[0]:SC0[0]:HE1:SE1] takes:
ffff888107804d20 (&fs_info->delayed_iput_lock){+.?.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline]
ffff888107804d20 (&fs_info->delayed_iput_lock){+.?.}-{2:2}, at: btrfs_run_delayed_iputs+0x28/0xe0 fs/btrfs/inode.c:3523
{IN-SOFTIRQ-W} state was registered at:
lock_acquire kernel/locking/lockdep.c:5761 [inline]
lock_acquire+0x1b1/0x520 kernel/locking/lockdep.c:5726
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:350 [inline]
btrfs_add_delayed_iput+0x128/0x390 fs/btrfs/inode.c:3490
btrfs_put_ordered_extent fs/btrfs/ordered-data.c:559 [inline]
btrfs_put_ordered_extent+0x2f6/0x610 fs/btrfs/ordered-data.c:547
__btrfs_bio_end_io fs/btrfs/bio.c:118 [inline]
__btrfs_bio_end_io+0x136/0x180 fs/btrfs/bio.c:112
btrfs_orig_bbio_end_io+0x86/0x2b0 fs/btrfs/bio.c:163
btrfs_simple_end_io+0x105/0x380 fs/btrfs/bio.c:378
bio_endio+0x589/0x690 block/bio.c:1617
req_bio_endio block/blk-mq.c:766 [inline]
blk_update_request+0x5c5/0x1620 block/blk-mq.c:911
blk_mq_end_request+0x59/0x680 block/blk-mq.c:1032
lo_complete_rq+0x1c6/0x280 drivers/block/loop.c:370
blk_complete_reqs+0xb3/0xf0 block/blk-mq.c:1110
__do_softirq+0x1d4/0x905 kernel/softirq.c:553
run_ksoftirqd kernel/softirq.c:921 [inline]
run_ksoftirqd+0x31/0x60 kernel/softirq.c:913
smpboot_thread_fn+0x659/0x9e0 kernel/smpboot.c:164
kthread+0x344/0x440 kernel/kthread.c:389
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
irq event stamp: 39
hardirqs last enabled at (39): [<ffffffff81d5ebc4>] __do_kmem_cache_free mm/slab.c:3558 [inline]
hardirqs last enabled at (39): [<ffffffff81d5ebc4>] kmem_cache_free mm/slab.c:3582 [inline]
hardirqs last enabled at (39): [<ffffffff81d5ebc4>] kmem_cache_free+0x244/0x370 mm/slab.c:3575
hardirqs last disabled at (38): [<ffffffff81d5eb5e>] __do_kmem_cache_free mm/slab.c:3553 [inline]
hardirqs last disabled at (38): [<ffffffff81d5eb5e>] kmem_cache_free mm/slab.c:3582 [inline]
hardirqs last disabled at (38): [<ffffffff81d5eb5e>] kmem_cache_free+0x1de/0x370 mm/slab.c:3575
softirqs last enabled at (0): [<ffffffff814ac99f>] copy_process+0x227f/0x75c0 kernel/fork.c:2448
softirqs last disabled at (0): [<0000000000000000>] 0x0
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&fs_info->delayed_iput_lock);
<Interrupt>
lock(&fs_info->delayed_iput_lock);
*** DEADLOCK ***
1 lock held by btrfs-cleaner/16079:
#0: ffff888107804860 (&fs_info->cleaner_mutex){+.+.}-{3:3}, at: cleaner_kthread+0x103/0x4b0 fs/btrfs/disk-io.c:1463
stack backtrace:
CPU: 3 PID: 16079 Comm: btrfs-cleaner Not tainted 6.4.0-syzkaller-09904-ga507db1d8fdc #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
print_usage_bug kernel/locking/lockdep.c:3978 [inline]
valid_state kernel/locking/lockdep.c:4020 [inline]
mark_lock_irq kernel/locking/lockdep.c:4223 [inline]
mark_lock.part.0+0x1102/0x1960 kernel/locking/lockdep.c:4685
mark_lock kernel/locking/lockdep.c:4649 [inline]
mark_usage kernel/locking/lockdep.c:4598 [inline]
__lock_acquire+0x8e4/0x5e20 kernel/locking/lockdep.c:5098
lock_acquire kernel/locking/lockdep.c:5761 [inline]
lock_acquire+0x1b1/0x520 kernel/locking/lockdep.c:5726
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:350 [inline]
btrfs_run_delayed_iputs+0x28/0xe0 fs/btrfs/inode.c:3523
cleaner_kthread+0x2e5/0x4b0 fs/btrfs/disk-io.c:1478
kthread+0x344/0x440 kernel/kthread.c:389
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
</TASK>
So fix this by using spin_lock_irq() and spin_unlock_irq() when running
delayed iputs, and using spin_lock_irqsave() and spin_unlock_irqrestore()
when adding a delayed iput().
Reported-by: syzbot+da501a04be5ff533b102@syzkaller.appspotmail.com
Fixes:
|
||
|---|---|---|
| .. | ||
| tests | ||
| accessors.c | ||
| accessors.h | ||
| acl.c | ||
| acl.h | ||
| async-thread.c | ||
| async-thread.h | ||
| backref.c | ||
| backref.h | ||
| bio.c | ||
| bio.h | ||
| block-group.c | ||
| block-group.h | ||
| block-rsv.c | ||
| block-rsv.h | ||
| btrfs_inode.h | ||
| check-integrity.c | ||
| check-integrity.h | ||
| compression.c | ||
| compression.h | ||
| ctree.c | ||
| ctree.h | ||
| defrag.c | ||
| defrag.h | ||
| delalloc-space.c | ||
| delalloc-space.h | ||
| delayed-inode.c | ||
| delayed-inode.h | ||
| delayed-ref.c | ||
| delayed-ref.h | ||
| dev-replace.c | ||
| dev-replace.h | ||
| dir-item.c | ||
| dir-item.h | ||
| discard.c | ||
| discard.h | ||
| disk-io.c | ||
| disk-io.h | ||
| export.c | ||
| export.h | ||
| extent_io.c | ||
| extent_io.h | ||
| extent_map.c | ||
| extent_map.h | ||
| extent-io-tree.c | ||
| extent-io-tree.h | ||
| extent-tree.c | ||
| extent-tree.h | ||
| file-item.c | ||
| file-item.h | ||
| file.c | ||
| file.h | ||
| free-space-cache.c | ||
| free-space-cache.h | ||
| free-space-tree.c | ||
| free-space-tree.h | ||
| fs.c | ||
| fs.h | ||
| inode-item.c | ||
| inode-item.h | ||
| inode.c | ||
| ioctl.c | ||
| ioctl.h | ||
| Kconfig | ||
| locking.c | ||
| locking.h | ||
| lru_cache.c | ||
| lru_cache.h | ||
| lzo.c | ||
| Makefile | ||
| messages.c | ||
| messages.h | ||
| misc.h | ||
| ordered-data.c | ||
| ordered-data.h | ||
| orphan.c | ||
| orphan.h | ||
| print-tree.c | ||
| print-tree.h | ||
| props.c | ||
| props.h | ||
| qgroup.c | ||
| qgroup.h | ||
| raid56.c | ||
| raid56.h | ||
| rcu-string.h | ||
| ref-verify.c | ||
| ref-verify.h | ||
| reflink.c | ||
| reflink.h | ||
| relocation.c | ||
| relocation.h | ||
| root-tree.c | ||
| root-tree.h | ||
| scrub.c | ||
| scrub.h | ||
| send.c | ||
| send.h | ||
| space-info.c | ||
| space-info.h | ||
| subpage.c | ||
| subpage.h | ||
| super.c | ||
| super.h | ||
| sysfs.c | ||
| sysfs.h | ||
| transaction.c | ||
| transaction.h | ||
| tree-checker.c | ||
| tree-checker.h | ||
| tree-log.c | ||
| tree-log.h | ||
| tree-mod-log.c | ||
| tree-mod-log.h | ||
| ulist.c | ||
| ulist.h | ||
| uuid-tree.c | ||
| uuid-tree.h | ||
| verity.c | ||
| verity.h | ||
| volumes.c | ||
| volumes.h | ||
| xattr.c | ||
| xattr.h | ||
| zlib.c | ||
| zoned.c | ||
| zoned.h | ||
| zstd.c | ||