linux-kernel - RE: [PATCH v2 05/14] mm: Introduce mf_dax_kill

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Date:   Wed, 24 Aug 2022 14:52:51 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     Shiyang Ruan <ruansy.fnst@...itsu.com>,
        <linux-kernel@...r.kernel.org>, <linux-xfs@...r.kernel.org>,
        <nvdimm@...ts.linux.dev>, <linux-mm@...ck.org>,
        <linux-fsdevel@...r.kernel.org>
CC:     <djwong@...nel.org>, <dan.j.williams@...el.com>,
        <david@...morbit.com>, <hch@...radead.org>,
        <akpm@...ux-foundation.org>, <jane.chu@...cle.com>,
        <rgoldwyn@...e.de>, <viro@...iv.linux.org.uk>,
        <willy@...radead.org>, <naoya.horiguchi@....com>,
        <linmiaohe@...wei.com>, Christoph Hellwig <hch@....de>
Subject: RE: [PATCH v2 05/14] mm: Introduce mf_dax_kill_procs() for fsdax case

Shiyang Ruan wrote:
> This new function is a variant of mf_generic_kill_procs that accepts a
> file, offset pair instead of a struct to support multiple files sharing
> a DAX mapping.  It is intended to be called by the file systems as part
> of the memory_failure handler after the file system performed a reverse
> mapping from the storage address to the file and file offset.
> 
> Signed-off-by: Shiyang Ruan <ruansy.fnst@...itsu.com>
> Reviewed-by: Dan Williams <dan.j.williams@...el.com>
> Reviewed-by: Christoph Hellwig <hch@....de>
> Reviewed-by: Darrick J. Wong <djwong@...nel.org>
> Reviewed-by: Miaohe Lin <linmiaohe@...wei.com>
> ---
>  include/linux/mm.h  |  2 +
>  mm/memory-failure.c | 96 ++++++++++++++++++++++++++++++++++++++++-----
>  2 files changed, 88 insertions(+), 10 deletions(-)

Unfortunately my test suite was only running the "non-destructive" set
of 'ndctl' tests which skipped some of the complex memory-failure cases.
Upon fixing that, bisect flags this commit as the source of the following
crash regression:

 kernel BUG at mm/memory-failure.c:310!
 invalid opcode: 0000 [#1] PREEMPT SMP PTI
 CPU: 26 PID: 1252 Comm: dax-pmd Tainted: G           OE     5.19.0-rc4+ #58
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
 RIP: 0010:add_to_kill+0x304/0x400
[..]
 Call Trace:
  <TASK>
  collect_procs.part.0+0x2c8/0x470
  memory_failure+0x979/0xf30
  do_madvise.part.0.cold+0x9c/0xd3
  ? lock_is_held_type+0xe3/0x140
  ? find_held_lock+0x2b/0x80
  ? lock_release+0x145/0x2f0
  ? lock_is_held_type+0xe3/0x140
  ? syscall_enter_from_user_mode+0x20/0x70
  __x64_sys_madvise+0x56/0x70
  do_syscall_64+0x3a/0x80
  entry_SYSCALL_64_after_hwframe+0x46/0xb0

This is from running:

  meson test -C build dax-ext4.sh

...from the ndctl repo.

I will take look, and posting it here in case I do not find it tonight
and Ruan can take a look.