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From: Matthew Wilcox <willy@infradead.org>
To: Song Liu <song@kernel.org>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux MM <linux-mm@kvack.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	William Kucharski <william.kucharski@oracle.com>,
	Hugh Dickins <hughd@google.com>
Subject: Re: [PATCH v2 1/2] mm, thp: check page mapping when truncating page cache
Date: Thu, 30 Sep 2021 01:00:41 +0100	[thread overview]
Message-ID: <YVT+KWFA8hfSKU+m@casper.infradead.org> (raw)
In-Reply-To: <CAPhsuW6_2_LxQRrs7xF3omgO22+6goDR=bEjKGRopaS-pHJB2Q@mail.gmail.com>

On Wed, Sep 29, 2021 at 04:41:48PM -0700, Song Liu wrote:
> The issue is NOT caused by concurrent khugepaged:collapse_file() and
> truncate_pagecache(inode, 0). With some printks, we can see a clear
> time gap (>2 second )  between collapse_file() finishes, and
> truncate_pagecache() (which crashes soon). Therefore, my earlier
> suggestion that adds deny_write_access() to collapse_file() does NOT
> work.
> 
> The crash is actually caused by concurrent truncate_pagecache(inode, 0).
> If I change the number of write thread in stress_madvise_dso.c to one,
> (IOW, one thread_read and one thread_write), I cannot reproduce the
> crash anymore.
> 
> I think this means we cannot fix this issue in collapse_file(), because it
> finishes long before the crash.

Ah!  So are we missing one or more of these locks:

	inode_lock(inode);
	filemap_invalidate_lock(mapping);

in the open path?


  reply	other threads:[~2021-09-30  0:03 UTC|newest]

Thread overview: 65+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-06 12:11 [PATCH 0/2] mm, thp: fix file-backed THP race in collapse_file Rongwei Wang
2021-09-06 12:11 ` [PATCH 1/2] mm, thp: check page mapping when truncating page cache Rongwei Wang
2021-09-07  2:49   ` Yu Xu
2021-09-07 18:08   ` Yang Shi
2021-09-08  2:35     ` Rongwei Wang
2021-09-08 21:48       ` Yang Shi
2021-09-09  1:25         ` Rongwei Wang
2021-09-13 14:49   ` [mm, thp] 20753096b6: BUG:unable_to_handle_page_fault_for_address kernel test robot
2021-09-06 12:12 ` [PATCH 2/2] mm, thp: bail out early in collapse_file for writeback page Rongwei Wang
2021-09-07 16:56   ` Yang Shi
2021-09-08  2:16     ` Rongwei Wang
2021-09-08 21:51       ` Yang Shi
2021-09-09  1:33         ` Rongwei Wang
2021-09-22  7:06 ` [PATCH v2 0/2] mm, thp: fix file-backed THP race in collapse_file and truncate pagecache Rongwei Wang
2021-09-22  7:06 ` [PATCH v2 1/2] mm, thp: check page mapping when truncating page cache Rongwei Wang
2021-09-22 11:37   ` Matthew Wilcox
2021-09-22 17:04     ` Rongwei Wang
2021-09-24  2:43       ` Andrew Morton
2021-09-24  3:08         ` Yang Shi
2021-09-24  3:35         ` Rongwei Wang
2021-09-24  7:12         ` Rongwei Wang
2021-09-27 22:24           ` Song Liu
2021-09-28 12:06             ` Matthew Wilcox
2021-09-28 16:59               ` Song Liu
2021-09-28 16:20             ` Rongwei Wang
2021-09-29  7:14               ` Song Liu
2021-09-29  7:50                 ` Rongwei Wang
2021-09-29 16:59                   ` Song Liu
2021-09-29 17:55                     ` Matthew Wilcox
2021-09-29 23:41                       ` Song Liu
2021-09-30  0:00                         ` Matthew Wilcox [this message]
2021-09-30  0:41                           ` Song Liu
2021-09-30  2:14                             ` Rongwei Wang
2021-10-04 17:26                             ` Rongwei Wang
2021-10-04 19:05                               ` Matthew Wilcox
2021-10-05  1:58                                 ` Rongwei Wang
2021-10-04 20:26                               ` Song Liu
2021-10-05  2:58                               ` Hugh Dickins
2021-10-05  3:07                                 ` Matthew Wilcox
2021-10-05  9:03                                 ` Rongwei Wang
2021-09-30  1:54                         ` Rongwei Wang
2021-09-30  3:26                           ` Song Liu
2021-09-30  5:24                             ` Hugh Dickins
2021-09-30 15:28                               ` Matthew Wilcox
2021-09-30 16:49                                 ` Hugh Dickins
2021-09-30 17:39                                   ` Yang Shi
2021-10-02 17:08                                     ` Matthew Wilcox
2021-10-04 18:28                                       ` Yang Shi
2021-10-04 19:31                                         ` Matthew Wilcox
2021-10-05  2:26                                           ` Hugh Dickins
2021-10-02  2:22                                   ` Rongwei Wang
2021-09-22  7:06 ` [PATCH v2 2/2] mm, thp: bail out early in collapse_file for writeback page Rongwei Wang
2021-10-06  2:18 ` [PATCH v3 v3 0/2] mm, thp: fix file-backed THP race in collapse_file and truncate pagecache Rongwei Wang
2021-10-06  2:18   ` [PATCH v3 v3 1/2] mm, thp: lock filemap when truncating page cache Rongwei Wang
2021-10-06  2:18   ` [PATCH v3 v3 2/2] mm, thp: bail out early in collapse_file for writeback page Rongwei Wang
2021-10-06  2:41     ` Matthew Wilcox
2021-10-06  8:39       ` Rongwei Wang
2021-10-06 17:58     ` Yang Shi
2021-10-11  2:22 ` [PATCH v4 0/2] mm, thp: fix file-backed THP race in collapse_file and truncate pagecache Rongwei Wang
2021-10-11  2:22   ` [PATCH v4 1/2] mm, thp: lock filemap when truncating page cache Rongwei Wang
2021-10-13  7:55     ` Rongwei Wang
2021-10-11  2:22   ` [PATCH v4 2/2] mm, thp: bail out early in collapse_file for writeback page Rongwei Wang
2021-10-11  3:08     ` Matthew Wilcox
2021-10-11  3:22       ` Rongwei Wang
2021-10-11  5:08     ` [PATCH v4 RESEND " Rongwei Wang

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