* btrfs BUG() in __set_extent_bit on GFP_ATOMIC failure.
@ 2014-08-08 4:26 Dave Jones
2014-08-08 14:43 ` Chris Mason
0 siblings, 1 reply; 2+ messages in thread
From: Dave Jones @ 2014-08-08 4:26 UTC (permalink / raw)
To: Chris Mason; +Cc: Linux Kernel
While playing with fault injection, I hit this quite easily.
kernel BUG at fs/btrfs/extent_io.c:990!
invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
CPU: 1 PID: 1270 Comm: fsx Not tainted 3.16.0+ #41
task: ffff88023fe46d60 ti: ffff8802405a8000 task.ti: ffff8802405a8000
RIP: 0010:[<ffffffffc0319af4>] [<ffffffffc0319af4>] __set_extent_bit+0x574/0x660 [btrfs]
...
[<ffffffff851be7fc>] ? set_track+0x9c/0x140
[<ffffffffc031aa94>] lock_extent_bits+0x94/0x310 [btrfs]
[<ffffffff85166454>] ? pagecache_get_page+0xb4/0x210
[<ffffffffc030d4de>] lock_and_cleanup_extent_if_need+0xee/0x1f0 [btrfs]
[<ffffffffc030e6e1>] __btrfs_buffered_write+0x1b1/0x680 [btrfs]
[<ffffffff850a258b>] ? preempt_count_sub+0xab/0x100
[<ffffffffc030ed2e>] btrfs_file_write_iter+0x17e/0x570 [btrfs]
[<ffffffff851d78ce>] new_sync_write+0x8e/0xd0
[<ffffffff851d8127>] vfs_write+0xb7/0x1f0
[<ffffffff851d8d68>] SyS_write+0x58/0xd0
[<ffffffff8576371f>] tracesys+0xdd/0xe2
989 prealloc = alloc_extent_state_atomic(prealloc);
990 BUG_ON(!prealloc);
541 static struct extent_state *
542 alloc_extent_state_atomic(struct extent_state *prealloc)
543 {
544 if (!prealloc)
545 prealloc = alloc_extent_state(GFP_ATOMIC);
546
547 return prealloc;
548 }
Going BUG() on a GFP_ATOMIC allocation failure seems a bit excessive.
Surely there's something better we can do here ?
Dave
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: btrfs BUG() in __set_extent_bit on GFP_ATOMIC failure.
2014-08-08 4:26 btrfs BUG() in __set_extent_bit on GFP_ATOMIC failure Dave Jones
@ 2014-08-08 14:43 ` Chris Mason
0 siblings, 0 replies; 2+ messages in thread
From: Chris Mason @ 2014-08-08 14:43 UTC (permalink / raw)
To: Dave Jones, Linux Kernel
On 08/08/2014 12:26 AM, Dave Jones wrote:
> While playing with fault injection, I hit this quite easily.
>
> kernel BUG at fs/btrfs/extent_io.c:990!
> invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
> CPU: 1 PID: 1270 Comm: fsx Not tainted 3.16.0+ #41
> task: ffff88023fe46d60 ti: ffff8802405a8000 task.ti: ffff8802405a8000
> RIP: 0010:[<ffffffffc0319af4>] [<ffffffffc0319af4>] __set_extent_bit+0x574/0x660 [btrfs]
> ...
> [<ffffffff851be7fc>] ? set_track+0x9c/0x140
> [<ffffffffc031aa94>] lock_extent_bits+0x94/0x310 [btrfs]
> [<ffffffff85166454>] ? pagecache_get_page+0xb4/0x210
> [<ffffffffc030d4de>] lock_and_cleanup_extent_if_need+0xee/0x1f0 [btrfs]
> [<ffffffffc030e6e1>] __btrfs_buffered_write+0x1b1/0x680 [btrfs]
> [<ffffffff850a258b>] ? preempt_count_sub+0xab/0x100
> [<ffffffffc030ed2e>] btrfs_file_write_iter+0x17e/0x570 [btrfs]
> [<ffffffff851d78ce>] new_sync_write+0x8e/0xd0
> [<ffffffff851d8127>] vfs_write+0xb7/0x1f0
> [<ffffffff851d8d68>] SyS_write+0x58/0xd0
> [<ffffffff8576371f>] tracesys+0xdd/0xe2
>
>
> 989 prealloc = alloc_extent_state_atomic(prealloc);
> 990 BUG_ON(!prealloc);
>
> 541 static struct extent_state *
> 542 alloc_extent_state_atomic(struct extent_state *prealloc)
> 543 {
> 544 if (!prealloc)
> 545 prealloc = alloc_extent_state(GFP_ATOMIC);
> 546
> 547 return prealloc;
> 548 }
>
>
> Going BUG() on a GFP_ATOMIC allocation failure seems a bit excessive.
> Surely there's something better we can do here ?
>
Ugh, yes we can. It should jump back to outside the lock and get the
prealloc there.
-chris
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2014-08-08 14:43 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2014-08-08 4:26 btrfs BUG() in __set_extent_bit on GFP_ATOMIC failure Dave Jones
2014-08-08 14:43 ` Chris Mason
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).