| Message ID | 1531374805-3325-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Please ignore this patch. The bug seems to be fixed by https://github.com/google/syzkaller/commit/06c33b3af0ff4072fb002879f83077c9d162a224 . On 2018/07/12 14:53, Tetsuo Handa wrote: > This is a temporary patch which should not go to linux.git. > > syzbot is hitting hung task problems at __sb_start_write() [1]. > atomic_long_read(&sem->rw_sem.count) says that percpu_down_read() was > blocked because somebody has called percpu_down_write(). But since we > believe that syzbot is not doing ioctl(FIFREEZE) requests, let's check > who is calling percpu_down_write() from freeze_super(). > > Since it is impossible to reproduce this problem locally, this patch was > made in order to test linux-next.git using syzbot infrastructure (and will > be removed after the culprit is found). > > [1] https://syzkaller.appspot.com/bug?id=287aa8708bc940d0ca1645223c53dd4c2d203be6 > > Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> > Cc: Dmitry Vyukov <dvyukov@google.com> > Cc: Alexander Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/super.c b/fs/super.c index 13647d4..4ec1b03 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1618,6 +1618,7 @@ int freeze_super(struct super_block *sb) return 0; } + WARN_ONCE(1, "Freezing superblock. Watch out for hung task.\n"); sb->s_writers.frozen = SB_FREEZE_WRITE; /* Release s_umount to preserve sb_start_write -> s_umount ordering */ up_write(&sb->s_umount);
This is a temporary patch which should not go to linux.git. syzbot is hitting hung task problems at __sb_start_write() [1]. atomic_long_read(&sem->rw_sem.count) says that percpu_down_read() was blocked because somebody has called percpu_down_write(). But since we believe that syzbot is not doing ioctl(FIFREEZE) requests, let's check who is calling percpu_down_write() from freeze_super(). Since it is impossible to reproduce this problem locally, this patch was made in order to test linux-next.git using syzbot infrastructure (and will be removed after the culprit is found). [1] https://syzkaller.appspot.com/bug?id=287aa8708bc940d0ca1645223c53dd4c2d203be6 Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> --- fs/super.c | 1 + 1 file changed, 1 insertion(+)