* Re: possible deadlock in shmem_fallocate (3)
@ 2019-09-10 7:18 Hillf Danton
0 siblings, 0 replies; 2+ messages in thread
From: Hillf Danton @ 2019-09-10 7:18 UTC (permalink / raw)
To: syzbot
Cc: hughd, linux-kernel, linux-mm, syzkaller-bugs, Peter Zijlstra,
Omar Sandoval
> syzbot found the following crash on Mon, 09 Sep 2019 20:38:05 -0700
>
> HEAD commit: 6d028043 Add linux-next specific files for 20190830
> git tree: linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=12359ec6600000
> kernel config: https://syzkaller.appspot.com/x/.config?x=82a6bec43ab0cb69
> dashboard link: https://syzkaller.appspot.com/bug?extid=5d04068d02b9da8a0947
> compiler: gcc (GCC) 9.0.0 20181231 (experimental)
>
> Unfortunately, I don't have any reproducer for this crash yet.
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+5d04068d02b9da8a0947@syzkaller.appspotmail.com
>
> ======================================================
> WARNING: possible circular locking dependency detected
> 5.3.0-rc6-next-20190830 #75 Not tainted
> ------------------------------------------------------
> kswapd0/1770 is trying to acquire lock:
> ffff8880a0b9b780 (&sb->s_type->i_mutex_key#13){+.+.}, at: inode_lock
> include/linux/fs.h:789 [inline]
> ffff8880a0b9b780 (&sb->s_type->i_mutex_key#13){+.+.}, at:
> shmem_fallocate+0x15a/0xc60 mm/shmem.c:2728
>
> but task is already holding lock:
> ffffffff89042f80 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x0/0x30
> mm/page_alloc.c:4889
>
> which lock already depends on the new lock.
>
>
> the existing dependency chain (in reverse order) is:
>
> -> #1 (fs_reclaim){+.+.}:
> __fs_reclaim_acquire mm/page_alloc.c:4075 [inline]
> fs_reclaim_acquire.part.0+0x24/0x30 mm/page_alloc.c:4086
> fs_reclaim_acquire mm/page_alloc.c:4662 [inline]
> prepare_alloc_pages mm/page_alloc.c:4659 [inline]
> __alloc_pages_nodemask+0x52f/0x900 mm/page_alloc.c:4711
> alloc_pages_vma+0x1bc/0x3f0 mm/mempolicy.c:2114
> shmem_alloc_page+0xbd/0x180 mm/shmem.c:1496
> shmem_alloc_and_acct_page+0x165/0x990 mm/shmem.c:1521
> shmem_getpage_gfp+0x598/0x2680 mm/shmem.c:1835
> shmem_getpage mm/shmem.c:152 [inline]
> shmem_write_begin+0x105/0x1e0 mm/shmem.c:2480
> generic_perform_write+0x23b/0x540 mm/filemap.c:3304
> __generic_file_write_iter+0x25e/0x630 mm/filemap.c:3433
> generic_file_write_iter+0x420/0x690 mm/filemap.c:3465
> call_write_iter include/linux/fs.h:1890 [inline]
> new_sync_write+0x4d3/0x770 fs/read_write.c:483
> __vfs_write+0xe1/0x110 fs/read_write.c:496
> vfs_write+0x268/0x5d0 fs/read_write.c:558
> ksys_write+0x14f/0x290 fs/read_write.c:611
> __do_sys_write fs/read_write.c:623 [inline]
> __se_sys_write fs/read_write.c:620 [inline]
> __x64_sys_write+0x73/0xb0 fs/read_write.c:620
> do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> -> #0 (&sb->s_type->i_mutex_key#13){+.+.}:
> check_prev_add kernel/locking/lockdep.c:2476 [inline]
> check_prevs_add kernel/locking/lockdep.c:2581 [inline]
> validate_chain kernel/locking/lockdep.c:2971 [inline]
> __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955
> lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487
> down_write+0x93/0x150 kernel/locking/rwsem.c:1534
> inode_lock include/linux/fs.h:789 [inline]
> shmem_fallocate+0x15a/0xc60 mm/shmem.c:2728
> ashmem_shrink_scan drivers/staging/android/ashmem.c:462 [inline]
> ashmem_shrink_scan+0x370/0x510 drivers/staging/android/ashmem.c:437
> do_shrink_slab+0x40f/0xa30 mm/vmscan.c:560
> shrink_slab mm/vmscan.c:721 [inline]
> shrink_slab+0x19a/0x680 mm/vmscan.c:694
> shrink_node+0x223/0x12e0 mm/vmscan.c:2807
> kswapd_shrink_node mm/vmscan.c:3549 [inline]
> balance_pgdat+0x57c/0xea0 mm/vmscan.c:3707
> kswapd+0x5c3/0xf30 mm/vmscan.c:3958
> kthread+0x361/0x430 kernel/kthread.c:255
> ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
>
> other info that might help us debug this:
>
> Possible unsafe locking scenario:
>
> CPU0 CPU1
> ---- ----
> lock(fs_reclaim);
> lock(&sb->s_type->i_mutex_key#13);
> lock(fs_reclaim);
> lock(&sb->s_type->i_mutex_key#13);
>
> *** DEADLOCK ***
>
> 2 locks held by kswapd0/1770:
> #0: ffffffff89042f80 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x0/0x30
> mm/page_alloc.c:4889
> #1: ffffffff8901ffe8 (shrinker_rwsem){++++}, at: shrink_slab
> mm/vmscan.c:711 [inline]
> #1: ffffffff8901ffe8 (shrinker_rwsem){++++}, at: shrink_slab+0xe6/0x680
> mm/vmscan.c:694
>
> stack backtrace:
> CPU: 0 PID: 1770 Comm: kswapd0 Not tainted 5.3.0-rc6-next-20190830 #75
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0x172/0x1f0 lib/dump_stack.c:113
> print_circular_bug.isra.0.cold+0x163/0x172 kernel/locking/lockdep.c:1685
> check_noncircular+0x32e/0x3e0 kernel/locking/lockdep.c:1809
> check_prev_add kernel/locking/lockdep.c:2476 [inline]
> check_prevs_add kernel/locking/lockdep.c:2581 [inline]
> validate_chain kernel/locking/lockdep.c:2971 [inline]
> __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955
> lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487
> down_write+0x93/0x150 kernel/locking/rwsem.c:1534
> inode_lock include/linux/fs.h:789 [inline]
> shmem_fallocate+0x15a/0xc60 mm/shmem.c:2728
> ashmem_shrink_scan drivers/staging/android/ashmem.c:462 [inline]
> ashmem_shrink_scan+0x370/0x510 drivers/staging/android/ashmem.c:437
> do_shrink_slab+0x40f/0xa30 mm/vmscan.c:560
> shrink_slab mm/vmscan.c:721 [inline]
> shrink_slab+0x19a/0x680 mm/vmscan.c:694
> shrink_node+0x223/0x12e0 mm/vmscan.c:2807
> kswapd_shrink_node mm/vmscan.c:3549 [inline]
> balance_pgdat+0x57c/0xea0 mm/vmscan.c:3707
> kswapd+0x5c3/0xf30 mm/vmscan.c:3958
> kthread+0x361/0x430 kernel/kthread.c:255
> ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
It burns more than pure cpu cycles to check anything against kswapd
in terms of __GFP_FS, so fix 93781325da6e and d92a8cfcb37e.
--- works/jj/vmscan.c 2019-09-10 14:52:00.602771300 +0800
+++ works/zz/vmscan.c 2019-09-10 14:54:48.101915500 +0800
@@ -3593,7 +3593,6 @@ static int balance_pgdat(pg_data_t *pgda
set_task_reclaim_state(current, &sc.reclaim_state);
psi_memstall_enter(&pflags);
- __fs_reclaim_acquire();
count_vm_event(PAGEOUTRUN);
@@ -3718,9 +3717,7 @@ restart:
wake_up_all(&pgdat->pfmemalloc_wait);
/* Check if kswapd should be suspending */
- __fs_reclaim_release();
ret = try_to_freeze();
- __fs_reclaim_acquire();
if (ret || kthread_should_stop())
break;
@@ -3770,7 +3767,6 @@ out:
}
snapshot_refaults(NULL, pgdat);
- __fs_reclaim_release();
psi_memstall_leave(&pflags);
set_task_reclaim_state(current, NULL);
--
^ permalink raw reply [flat|nested] 2+ messages in thread
* possible deadlock in shmem_fallocate (3)
@ 2019-09-10 3:38 syzbot
0 siblings, 0 replies; 2+ messages in thread
From: syzbot @ 2019-09-10 3:38 UTC (permalink / raw)
To: hughd, linux-kernel, linux-mm, syzkaller-bugs
Hello,
syzbot found the following crash on:
HEAD commit: 6d028043 Add linux-next specific files for 20190830
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=12359ec6600000
kernel config: https://syzkaller.appspot.com/x/.config?x=82a6bec43ab0cb69
dashboard link: https://syzkaller.appspot.com/bug?extid=5d04068d02b9da8a0947
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
Unfortunately, I don't have any reproducer for this crash yet.
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+5d04068d02b9da8a0947@syzkaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
5.3.0-rc6-next-20190830 #75 Not tainted
------------------------------------------------------
kswapd0/1770 is trying to acquire lock:
ffff8880a0b9b780 (&sb->s_type->i_mutex_key#13){+.+.}, at: inode_lock
include/linux/fs.h:789 [inline]
ffff8880a0b9b780 (&sb->s_type->i_mutex_key#13){+.+.}, at:
shmem_fallocate+0x15a/0xc60 mm/shmem.c:2728
but task is already holding lock:
ffffffff89042f80 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x0/0x30
mm/page_alloc.c:4889
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (fs_reclaim){+.+.}:
__fs_reclaim_acquire mm/page_alloc.c:4075 [inline]
fs_reclaim_acquire.part.0+0x24/0x30 mm/page_alloc.c:4086
fs_reclaim_acquire mm/page_alloc.c:4662 [inline]
prepare_alloc_pages mm/page_alloc.c:4659 [inline]
__alloc_pages_nodemask+0x52f/0x900 mm/page_alloc.c:4711
alloc_pages_vma+0x1bc/0x3f0 mm/mempolicy.c:2114
shmem_alloc_page+0xbd/0x180 mm/shmem.c:1496
shmem_alloc_and_acct_page+0x165/0x990 mm/shmem.c:1521
shmem_getpage_gfp+0x598/0x2680 mm/shmem.c:1835
shmem_getpage mm/shmem.c:152 [inline]
shmem_write_begin+0x105/0x1e0 mm/shmem.c:2480
generic_perform_write+0x23b/0x540 mm/filemap.c:3304
__generic_file_write_iter+0x25e/0x630 mm/filemap.c:3433
generic_file_write_iter+0x420/0x690 mm/filemap.c:3465
call_write_iter include/linux/fs.h:1890 [inline]
new_sync_write+0x4d3/0x770 fs/read_write.c:483
__vfs_write+0xe1/0x110 fs/read_write.c:496
vfs_write+0x268/0x5d0 fs/read_write.c:558
ksys_write+0x14f/0x290 fs/read_write.c:611
__do_sys_write fs/read_write.c:623 [inline]
__se_sys_write fs/read_write.c:620 [inline]
__x64_sys_write+0x73/0xb0 fs/read_write.c:620
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
-> #0 (&sb->s_type->i_mutex_key#13){+.+.}:
check_prev_add kernel/locking/lockdep.c:2476 [inline]
check_prevs_add kernel/locking/lockdep.c:2581 [inline]
validate_chain kernel/locking/lockdep.c:2971 [inline]
__lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955
lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487
down_write+0x93/0x150 kernel/locking/rwsem.c:1534
inode_lock include/linux/fs.h:789 [inline]
shmem_fallocate+0x15a/0xc60 mm/shmem.c:2728
ashmem_shrink_scan drivers/staging/android/ashmem.c:462 [inline]
ashmem_shrink_scan+0x370/0x510 drivers/staging/android/ashmem.c:437
do_shrink_slab+0x40f/0xa30 mm/vmscan.c:560
shrink_slab mm/vmscan.c:721 [inline]
shrink_slab+0x19a/0x680 mm/vmscan.c:694
shrink_node+0x223/0x12e0 mm/vmscan.c:2807
kswapd_shrink_node mm/vmscan.c:3549 [inline]
balance_pgdat+0x57c/0xea0 mm/vmscan.c:3707
kswapd+0x5c3/0xf30 mm/vmscan.c:3958
kthread+0x361/0x430 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(fs_reclaim);
lock(&sb->s_type->i_mutex_key#13);
lock(fs_reclaim);
lock(&sb->s_type->i_mutex_key#13);
*** DEADLOCK ***
2 locks held by kswapd0/1770:
#0: ffffffff89042f80 (fs_reclaim){+.+.}, at: __fs_reclaim_acquire+0x0/0x30
mm/page_alloc.c:4889
#1: ffffffff8901ffe8 (shrinker_rwsem){++++}, at: shrink_slab
mm/vmscan.c:711 [inline]
#1: ffffffff8901ffe8 (shrinker_rwsem){++++}, at: shrink_slab+0xe6/0x680
mm/vmscan.c:694
stack backtrace:
CPU: 0 PID: 1770 Comm: kswapd0 Not tainted 5.3.0-rc6-next-20190830 #75
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x172/0x1f0 lib/dump_stack.c:113
print_circular_bug.isra.0.cold+0x163/0x172 kernel/locking/lockdep.c:1685
check_noncircular+0x32e/0x3e0 kernel/locking/lockdep.c:1809
check_prev_add kernel/locking/lockdep.c:2476 [inline]
check_prevs_add kernel/locking/lockdep.c:2581 [inline]
validate_chain kernel/locking/lockdep.c:2971 [inline]
__lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955
lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487
down_write+0x93/0x150 kernel/locking/rwsem.c:1534
inode_lock include/linux/fs.h:789 [inline]
shmem_fallocate+0x15a/0xc60 mm/shmem.c:2728
ashmem_shrink_scan drivers/staging/android/ashmem.c:462 [inline]
ashmem_shrink_scan+0x370/0x510 drivers/staging/android/ashmem.c:437
do_shrink_slab+0x40f/0xa30 mm/vmscan.c:560
shrink_slab mm/vmscan.c:721 [inline]
shrink_slab+0x19a/0x680 mm/vmscan.c:694
shrink_node+0x223/0x12e0 mm/vmscan.c:2807
kswapd_shrink_node mm/vmscan.c:3549 [inline]
balance_pgdat+0x57c/0xea0 mm/vmscan.c:3707
kswapd+0x5c3/0xf30 mm/vmscan.c:3958
kthread+0x361/0x430 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.
syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
^ permalink raw reply [flat|nested] 2+ messages in thread
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