On Wed, Jan 24, 2018 at 11:33:08AM +0800, Lu Fengqi wrote:
> On Tue, Jan 23, 2018 at 10:22:09PM -0500, Zygo Blaxell wrote:
> >Until v4.14, this warning was very infrequent:
> >
> > WARNING: CPU: 3 PID: 18172 at fs/btrfs/backref.c:1391 find_parent_nodes+0xc41/0x14e0
> > Modules linked in: [...]
> > CPU: 3 PID: 18172 Comm: bees Tainted: G D W L 4.11.9-zb64+ #1
> > Hardware name: System manufacturer System Product Name/M5A78L-M/USB3, BIOS 2101 12/02/2014
> > Call Trace:
> > dump_stack+0x85/0xc2
> > __warn+0xd1/0xf0
> > warn_slowpath_null+0x1d/0x20
> > find_parent_nodes+0xc41/0x14e0
> > __btrfs_find_all_roots+0xad/0x120
> > ? extent_same_check_offsets+0x70/0x70
> > iterate_extent_inodes+0x168/0x300
> > iterate_inodes_from_logical+0x87/0xb0
> > ? iterate_inodes_from_logical+0x87/0xb0
> > ? extent_same_check_offsets+0x70/0x70
> > btrfs_ioctl+0x8ac/0x2820
> > ? lock_acquire+0xc2/0x200
> > do_vfs_ioctl+0x91/0x700
> > ? __fget+0x112/0x200
> > SyS_ioctl+0x79/0x90
> > entry_SYSCALL_64_fastpath+0x23/0xc6
> > ? trace_hardirqs_off_caller+0x1f/0x140
> >
> >Starting with v4.14 (specifically 86d5f9944252 ("btrfs: convert prelimary
> >reference tracking to use rbtrees")) the WARN_ON occurs three orders of
> >magnitude more frequently--almost once per second while running workloads
> >like bees.
> >
> >Replace the WARN_ON() with a comment rationale for its removal.
> >The rationale is paraphrased from an explanation by Edmund Nadolski
> ><enadolski@xxxxxxx> on the linux-btrfs mailing list.
> >
> >Fixes: 8da6d5815c59 ("Btrfs: added btrfs_find_all_roots()")
> >Signed-off-by: Zygo Blaxell <ce3g8jdj@xxxxxxxxxxxxxxxxxxxxx>
>
> Reviewed-by: Lu Fengqi <lufq.fnst@xxxxxxxxxxxxxx>
Added to next, thanks.
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