Re: [xfs] db962cd266: Assertion_failed

From: Dave Chinner
Date: Fri Jan 01 2021 - 16:58:03 EST


On Fri, Jan 01, 2021 at 05:10:49PM +0800, Yafang Shao wrote:
> On Thu, Dec 31, 2020 at 10:46 AM kernel test robot
> <oliver.sang@xxxxxxxxx> wrote:
.....
> > [ 552.905799] XFS: Assertion failed: !current->journal_info, file: fs/xfs/xfs_trans.h, line: 280
> > [ 553.104459] xfs_trans_reserve+0x225/0x320 [xfs]
> > [ 553.110556] xfs_trans_roll+0x6e/0xe0 [xfs]
> > [ 553.116134] xfs_defer_trans_roll+0x104/0x2a0 [xfs]
> > [ 553.122489] ? xfs_extent_free_create_intent+0x62/0xc0 [xfs]
> > [ 553.129780] xfs_defer_finish_noroll+0xb8/0x620 [xfs]
> > [ 553.136299] xfs_defer_finish+0x11/0xa0 [xfs]
> > [ 553.142017] xfs_itruncate_extents_flags+0x141/0x440 [xfs]
> > [ 553.149053] xfs_setattr_size+0x3da/0x480 [xfs]
> > [ 553.154939] ? setattr_prepare+0x6a/0x1e0
> > [ 553.160250] xfs_vn_setattr+0x70/0x120 [xfs]
> > [ 553.165833] notify_change+0x364/0x500
> > [ 553.170820] ? do_truncate+0x76/0xe0
> > [ 553.175673] do_truncate+0x76/0xe0
> > [ 553.180184] path_openat+0xe6c/0x10a0
> > [ 553.184981] do_filp_open+0x91/0x100
> > [ 553.189707] ? __check_object_size+0x136/0x160
> > [ 553.195493] do_sys_openat2+0x20d/0x2e0
> > [ 553.200481] do_sys_open+0x44/0x80
> > [ 553.204926] do_syscall_64+0x33/0x40
> > [ 553.209588] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> Thanks for the report.
>
> At a first glance, it seems we should make a similar change as we did
> in xfs_trans_context_clear().
>
> static inline void
> xfs_trans_context_set(struct xfs_trans *tp)
> {
> /*
> * We have already handed over the context via xfs_trans_context_swap().
> */
> if (current->journal_info)
> return;
> current->journal_info = tp;
> tp->t_pflags = memalloc_nofs_save();
> }

Ah, no.

Remember how I said "split out the wrapping of transaction
context setup in xfs_trans_reserve() from
the lifting of the context setting into xfs_trans_alloc()"?

Well, you did the former and dropped the latter out of the patch
set.

Now when a transaction rolls after xfs_trans_context_swap(), it
calls xfs_trans_reserve() and tries to do transaction context setup
work inside a transaction context that already exists. IOWs, you
need to put the patch that lifts of the context setting up into
xfs_trans_alloc() back into the patchset before adding the
current->journal functionality patch.

Also, you need to test XFS code with CONFIG_XFS_DEBUG=y so that
asserts are actually built into the code and exercised, because this
ASSERT should have fired on the first rolling transaction that the
kernel executes...

Cheers,

Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx