From: Linus Torvalds <torvalds@linux-foundation.org>
To: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>,
syzbot <syzbot+3622cea378100f45d59f@syzkaller.appspotmail.com>,
Andreas Dilger <adilger.kernel@dilger.ca>,
Ext4 Developers List <linux-ext4@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
"Theodore Ts'o" <tytso@mit.edu>, Linux-MM <linux-mm@kvack.org>,
Oleg Nesterov <oleg@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Nicholas Piggin <npiggin@gmail.com>,
Alex Shi <alex.shi@linux.alibaba.com>, Qian Cai <cai@lca.pw>,
Christoph Hellwig <hch@infradead.org>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Matthew Wilcox <willy@infradead.org>,
William Kucharski <william.kucharski@oracle.com>,
Jens Axboe <axboe@kernel.dk>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-xfs <linux-xfs@vger.kernel.org>
Subject: Re: kernel BUG at fs/ext4/inode.c:LINE!
Date: Mon, 23 Nov 2020 20:26:48 -0800 [thread overview]
Message-ID: <CAHk-=wjcSFM+aqLnh7ucx3_tHpc1+9sJ+FfhSgVFH316uX2FZQ@mail.gmail.com> (raw)
In-Reply-To: <alpine.LSU.2.11.2011231928140.4305@eggly.anvils>
On Mon, Nov 23, 2020 at 8:07 PM Hugh Dickins <hughd@google.com> wrote:
>
> The problem is that PageWriteback is not accompanied by a page reference
> (as the NOTE at the end of test_clear_page_writeback() acknowledges): as
> soon as TestClearPageWriteback has been done, that page could be removed
> from page cache, freed, and reused for something else by the time that
> wake_up_page() is reached.
Ugh.
Would it be possible to instead just make PageWriteback take the ref?
I don't hate your patch per se, but looking at that long explanation,
and looking at the gyrations end_page_writeback() does, I go "why
don't we do that?"
IOW, why couldn't we just make the __test_set_page_writeback()
increment the page count if the writeback flag wasn't already set, and
then make the end_page_writeback() do a put_page() after it all?
Linus
next prev parent reply other threads:[~2020-11-24 4:27 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <000000000000d3a33205add2f7b2@google.com>
2020-08-28 10:07 ` Jan Kara
2020-08-31 10:03 ` Jan Kara
2020-08-31 18:21 ` Linus Torvalds
2020-11-24 4:07 ` Hugh Dickins
2020-11-24 4:26 ` Linus Torvalds [this message]
2020-11-24 4:53 ` Linus Torvalds
2020-11-24 6:34 ` Hugh Dickins
2020-11-24 16:46 ` Hugh Dickins
2020-11-24 12:19 ` Matthew Wilcox
2020-11-24 16:28 ` Hugh Dickins
2020-11-24 18:33 ` Matthew Wilcox
2020-11-24 19:00 ` Linus Torvalds
2020-11-24 20:15 ` Matthew Wilcox
2020-11-24 20:34 ` Linus Torvalds
2020-11-24 21:46 ` Hugh Dickins
2020-11-24 23:24 ` Linus Torvalds
2020-11-25 21:30 ` Linus Torvalds
2020-11-25 22:01 ` Linus Torvalds
2020-11-25 9:20 ` Jan Kara
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