[syzbot] [ext4?] BUG: sleeping function called from invalid context in alloc_buffer_head

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 52025ebbb518 Add linux-next specific files for 20230508
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=10c27582280000
kernel config: https://syzkaller.appspot.com/x/.config?x=d1f55a88ec660cdb
dashboard link: https://syzkaller.appspot.com/bug?extid=3c6cac1550288f8e7060
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/912ed8ef786f/disk-52025ebb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d53b6c9decdc/vmlinux-52025ebb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f0d8a6edd999/bzImage-52025ebb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3c6cac...@syzkaller.appspotmail.com

BUG: sleeping function called from invalid context at include/linux/sched/mm.h:306
in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 4439, name: syslogd
preempt_count: 0, expected: 0
RCU nest depth: 1, expected: 0
2 locks held by syslogd/4439:
#0: ffff888085665e00 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:785 [inline]
#0: ffff888085665e00 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: lookup_slow fs/namei.c:1706 [inline]
#0: ffff888085665e00 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: walk_component+0x332/0x5a0 fs/namei.c:1998
#1: ffffffff8c799800 (rcu_read_lock){....}-{1:2}, at: lru_gen_refault mm/workingset.c:293 [inline]
#1: ffffffff8c799800 (rcu_read_lock){....}-{1:2}, at: workingset_refault+0x175/0x11e0 mm/workingset.c:528
CPU: 1 PID: 4439 Comm: syslogd Not tainted 6.4.0-rc1-next-20230508-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x136/0x150 lib/dump_stack.c:106
__might_resched+0x358/0x580 kernel/sched/core.c:10153
might_alloc include/linux/sched/mm.h:306 [inline]
slab_pre_alloc_hook mm/slab.h:670 [inline]
slab_alloc_node mm/slub.c:3433 [inline]
slab_alloc mm/slub.c:3459 [inline]
__kmem_cache_alloc_lru mm/slub.c:3466 [inline]
kmem_cache_alloc+0x357/0x3b0 mm/slub.c:3475
kmem_cache_zalloc include/linux/slab.h:670 [inline]
alloc_buffer_head+0x24/0x150 fs/buffer.c:3044
folio_alloc_buffers+0x2f2/0x810 fs/buffer.c:941
alloc_page_buffers fs/buffer.c:976 [inline]
grow_dev_page fs/buffer.c:1084 [inline]
grow_buffers fs/buffer.c:1130 [inline]
__getblk_slow+0x612/0x1230 fs/buffer.c:1157
__getblk_gfp+0x72/0x80 fs/buffer.c:1452
sb_getblk include/linux/buffer_head.h:369 [inline]
ext4_getblk+0x211/0x850 fs/ext4/inode.c:845
ext4_bread_batch+0x82/0x500 fs/ext4/inode.c:912
__ext4_find_entry+0x451/0x1050 fs/ext4/namei.c:1650
ext4_lookup_entry fs/ext4/namei.c:1751 [inline]
ext4_lookup fs/ext4/namei.c:1819 [inline]
ext4_lookup+0x500/0x700 fs/ext4/namei.c:1810
__lookup_slow+0x24c/0x460 fs/namei.c:1690
lookup_slow fs/namei.c:1707 [inline]
walk_component+0x33f/0x5a0 fs/namei.c:1998
link_path_walk.part.0+0x74e/0xd60 fs/namei.c:2325
link_path_walk fs/namei.c:2250 [inline]
path_openat+0x25c/0x2750 fs/namei.c:3787
do_filp_open+0x1ba/0x410 fs/namei.c:3818
do_sys_openat2+0x16d/0x4c0 fs/open.c:1356
do_sys_open fs/open.c:1372 [inline]
__do_sys_openat fs/open.c:1388 [inline]
__se_sys_openat fs/open.c:1383 [inline]
__x64_sys_openat+0x143/0x1f0 fs/open.c:1383
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f97344a89a4
Code: 24 20 48 8d 44 24 30 48 89 44 24 28 64 8b 04 25 18 00 00 00 85 c0 75 2c 44 89 e2 48 89 ee bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 76 60 48 8b 15 55 a4 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffc296981d0 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 000055d433717910 RCX: 00007f97344a89a4
RDX: 0000000000000d41 RSI: 00007f9734647443 RDI: 00000000ffffff9c
RBP: 00007f9734647443 R08: 0000000000000001 R09: 0000000000000000
R10: 00000000000001b6 R11: 0000000000000246 R12: 0000000000000d41
R13: 000000006459d39e R14: 0000000000000005 R15: 000055d433717a60
</TASK>
BUG: sleeping function called from invalid context at include/linux/buffer_head.h:408
in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 4439, name: syslogd
preempt_count: 0, expected: 0
RCU nest depth: 1, expected: 0
2 locks held by syslogd/4439:
#0: ffff888085665e00 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:785 [inline]
#0: ffff888085665e00 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: lookup_slow fs/namei.c:1706 [inline]
#0: ffff888085665e00 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: walk_component+0x332/0x5a0 fs/namei.c:1998
#1: ffffffff8c799800 (rcu_read_lock){....}-{1:2}, at: lru_gen_refault mm/workingset.c:293 [inline]
#1: ffffffff8c799800 (rcu_read_lock){....}-{1:2}, at: workingset_refault+0x175/0x11e0 mm/workingset.c:528
CPU: 1 PID: 4439 Comm: syslogd Tainted: G W 6.4.0-rc1-next-20230508-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x136/0x150 lib/dump_stack.c:106
__might_resched+0x358/0x580 kernel/sched/core.c:10153
lock_buffer include/linux/buffer_head.h:408 [inline]
ext4_read_bh_lock+0x28/0xc0 fs/ext4/super.c:208
ext4_bread_batch+0x2cc/0x500 fs/ext4/inode.c:923
__ext4_find_entry+0x451/0x1050 fs/ext4/namei.c:1650
ext4_lookup_entry fs/ext4/namei.c:1751 [inline]
ext4_lookup fs/ext4/namei.c:1819 [inline]
ext4_lookup+0x500/0x700 fs/ext4/namei.c:1810
__lookup_slow+0x24c/0x460 fs/namei.c:1690
lookup_slow fs/namei.c:1707 [inline]
walk_component+0x33f/0x5a0 fs/namei.c:1998
link_path_walk.part.0+0x74e/0xd60 fs/namei.c:2325
link_path_walk fs/namei.c:2250 [inline]
path_openat+0x25c/0x2750 fs/namei.c:3787
do_filp_open+0x1ba/0x410 fs/namei.c:3818
do_sys_openat2+0x16d/0x4c0 fs/open.c:1356
do_sys_open fs/open.c:1372 [inline]
__do_sys_openat fs/open.c:1388 [inline]
__se_sys_openat fs/open.c:1383 [inline]
__x64_sys_openat+0x143/0x1f0 fs/open.c:1383
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f97344a89a4
Code: 24 20 48 8d 44 24 30 48 89 44 24 28 64 8b 04 25 18 00 00 00 85 c0 75 2c 44 89 e2 48 89 ee bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 76 60 48 8b 15 55 a4 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffc296981d0 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 000055d433717910 RCX: 00007f97344a89a4
RDX: 0000000000000d41 RSI: 00007f9734647443 RDI: 00000000ffffff9c
RBP: 00007f9734647443 R08: 0000000000000001 R09: 0000000000000000
R10: 00000000000001b6 R11: 0000000000000246 R12: 0000000000000d41
R13: 000000006459d39e R14: 0000000000000005 R15: 000055d433717a60
</TASK>
------------[ cut here ]------------
Voluntary context switch within RCU read-side critical section!
WARNING: CPU: 0 PID: 4439 at kernel/rcu/tree_plugin.h:318 rcu_note_context_switch+0xbb9/0x1800 kernel/rcu/tree_plugin.h:318
Modules linked in:
CPU: 0 PID: 4439 Comm: syslogd Tainted: G W 6.4.0-rc1-next-20230508-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
RIP: 0010:rcu_note_context_switch+0xbb9/0x1800 kernel/rcu/tree_plugin.h:318
Code: 9d d0 67 00 4c 8b 4c 24 30 8b 4c 24 28 48 8b 54 24 20 e9 8f 03 00 00 48 c7 c7 e0 2f 4e 8a c6 05 19 97 f5 0c 01 e8 67 bb dc ff <0f> 0b e9 4c f5 ff ff 81 e5 ff ff ff 7f 0f 84 d7 f6 ff ff 65 48 8b
RSP: 0018:ffffc9000312f210 EFLAGS: 00010086
RAX: 0000000000000000 RBX: ffff8880b983d4c0 RCX: 0000000000000000
RDX: ffff88806a4b1dc0 RSI: ffffffff814bf407 RDI: 0000000000000001
RBP: ffff88806a4b1dc0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 00000000000186c8 R12: 0000000000000000
R13: ffff88806a4b1dc0 R14: ffffffff8e7abcf0 R15: ffff8880b983c5c0
FS: 00007f9734354380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007feeab7831b8 CR3: 000000002780a000 CR4: 00000000003506f0
DR0: 00000000ffff070c DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__schedule+0x276/0x5790 kernel/sched/core.c:6569
schedule+0xde/0x1a0 kernel/sched/core.c:6745
io_schedule+0xbe/0x130 kernel/sched/core.c:8979
bit_wait_io+0x16/0xe0 kernel/sched/wait_bit.c:209
__wait_on_bit+0x64/0x180 kernel/sched/wait_bit.c:49
out_of_line_wait_on_bit+0xd9/0x110 kernel/sched/wait_bit.c:64
wait_on_bit_io include/linux/wait_bit.h:101 [inline]
__wait_on_buffer+0x63/0x70 fs/buffer.c:123
wait_on_buffer include/linux/buffer_head.h:398 [inline]
__ext4_find_entry+0x590/0x1050 fs/ext4/namei.c:1660
ext4_lookup_entry fs/ext4/namei.c:1751 [inline]
ext4_lookup fs/ext4/namei.c:1819 [inline]
ext4_lookup+0x500/0x700 fs/ext4/namei.c:1810
__lookup_slow+0x24c/0x460 fs/namei.c:1690
lookup_slow fs/namei.c:1707 [inline]
walk_component+0x33f/0x5a0 fs/namei.c:1998
link_path_walk.part.0+0x74e/0xd60 fs/namei.c:2325
link_path_walk fs/namei.c:2250 [inline]
path_openat+0x25c/0x2750 fs/namei.c:3787
do_filp_open+0x1ba/0x410 fs/namei.c:3818
do_sys_openat2+0x16d/0x4c0 fs/open.c:1356
do_sys_open fs/open.c:1372 [inline]
__do_sys_openat fs/open.c:1388 [inline]
__se_sys_openat fs/open.c:1383 [inline]
__x64_sys_openat+0x143/0x1f0 fs/open.c:1383
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f97344a89a4
Code: 24 20 48 8d 44 24 30 48 89 44 24 28 64 8b 04 25 18 00 00 00 85 c0 75 2c 44 89 e2 48 89 ee bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 76 60 48 8b 15 55 a4 0d 00 f7 d8 64 89 02 48 83
RSP: 002b:00007ffc296981d0 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 000055d433717910 RCX: 00007f97344a89a4
RDX: 0000000000000d41 RSI: 00007f9734647443 RDI: 00000000ffffff9c
RBP: 00007f9734647443 R08: 0000000000000001 R09: 0000000000000000
R10: 00000000000001b6 R11: 0000000000000246 R12: 0000000000000d41
R13: 000000006459d39e R14: 0000000000000005 R15: 000055d433717a60
</TASK>


---
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If the bug is already fixed, let syzbot know by replying with:
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If you want to change bug's subsystems, reply with:
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(See the list of subsystem names on the web dashboard)

If the bug is a duplicate of another bug, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[Tetsuo Handa]

syzbot is reporting sleep in RCU context, for commit d66c718d28ac
("workingset: refactor LRU refault to expose refault recency check")
missed rcu_read_unlock().

Reported-by: syzbot <syzbot+3c6cac...@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=3c6cac1550288f8e7060
Signed-off-by: Tetsuo Handa <penguin...@I-love.SAKURA.ne.jp>
Fixes: d66c718d28ac ("workingset: refactor LRU refault to expose refault recency check")
---
mm/workingset.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/workingset.c b/mm/workingset.c
index d81f9dafc9f1..90ae785d4c9c 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -303,7 +303,7 @@ static void lru_gen_refault(struct folio *folio, void *shadow)
goto unlock;

if (pgdat != folio_pgdat(folio))
- return;
+ goto unlock;

lruvec = mem_cgroup_lruvec(memcg, pgdat);
lrugen = &lruvec->lrugen;
--
2.18.4

[Johannes Weiner]

On Wed, May 10, 2023 at 07:22:55AM +0900, Tetsuo Handa wrote:
> syzbot is reporting sleep in RCU context, for commit d66c718d28ac
> ("workingset: refactor LRU refault to expose refault recency check")
> missed rcu_read_unlock().
>
> Reported-by: syzbot <syzbot+3c6cac...@syzkaller.appspotmail.com>
> Closes: https://syzkaller.appspot.com/bug?extid=3c6cac1550288f8e7060
> Signed-off-by: Tetsuo Handa <penguin...@I-love.SAKURA.ne.jp>
> Fixes: d66c718d28ac ("workingset: refactor LRU refault to expose refault recency check")

Oops! Thanks for the fix.

Acked-by: Johannes Weiner <han...@cmpxchg.org>

[Nhat Pham]

Thanks for the fix!

Acked-by: Nhat Pham <nph...@gmail.com>

[Theodore Ts'o]

#syz set: subsystems mm

[syzbot]

> #syz set: subsystems mm

The specified label "mm" is unknown.
Please use one of the supported labels.

The following labels are suported:
missing-backport, no-reminders, prio: {low, normal, high}, subsystems: {.. see below ..}
The list of subsystems: https://syzkaller.appspot.com/upstream/subsystems?all=true

[Aleksandr Nogikh]

#syz set subsystems: mm

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