Messages in this thread | | | Date | Thu, 21 Oct 2021 20:11:20 +0800 | Subject | Re: [f2fs-dev] [PATCH] f2fs: remove circular locking between sb_internal and fs_reclaim | From | Chao Yu <> |
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On 2021/10/15 3:05, Daeho Jeong wrote: > From: Daeho Jeong <daehojeong@google.com> > > We detected the below circular locking dependency between sb_internal > and fs_reclaim. So, removed it by calling dquot_initialize() before > sb_start_intwrite(). > > ====================================================== > WARNING: possible circular locking dependency detected > ------------------------------------------------------ > kswapd0/133 is trying to acquire lock: > ffffff80d5fb9680 (sb_internal#2){.+.+}-{0:0}, at: evict+0xd4/0x2f8 > > but task is already holding lock: > ffffffda597c93a8 (fs_reclaim){+.+.}-{0:0}, at: > __fs_reclaim_acquire+0x4/0x50 > > which lock already depends on the new lock. > ... > other info that might help us debug this: > > Chain exists of: > > sb_internal#2 --> &s->s_dquot.dqio_sem --> fs_reclaim > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > lock(fs_reclaim); > lock(&s->s_dquot.dqio_sem); > lock(fs_reclaim); > lock(sb_internal#2);
Sorry, I still didn't get the root cause of this deadlock issue, could you please explain more about this?
And why calling dquot_initialize() in drop_inode() could break the circular locking dependency?
Thanks,
> > Signed-off-by: Daeho Jeong <daehojeong@google.com> > --- > fs/f2fs/super.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c > index 86eeb019cc52..a133932333c5 100644 > --- a/fs/f2fs/super.c > +++ b/fs/f2fs/super.c > @@ -1370,6 +1370,8 @@ static int f2fs_drop_inode(struct inode *inode) > /* should remain fi->extent_tree for writepage */ > f2fs_destroy_extent_node(inode); > > + dquot_initialize(inode); > + > sb_start_intwrite(inode->i_sb); > f2fs_i_size_write(inode, 0); > >
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