From: Matthew Wilcox <willy@infradead.org>
To: Yang Shi <shy828301@gmail.com>
Cc: syzbot <syzbot+1f52b3a18d5633fa7f82@syzkaller.appspotmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Alistair Popple <apopple@nvidia.com>,
chinwen.chang@mediatek.com, fgheet255t@gmail.com,
Jann Horn <jannh@google.com>,
Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux MM <linux-mm@kvack.org>, Peter Xu <peterx@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
syzkaller-bugs@googlegroups.com, tonymarislogistics@yandex.com,
Vlastimil Babka <vbabka@suse.cz>,
walken@google.com, Zi Yan <ziy@nvidia.com>
Subject: Re: [syzbot] kernel BUG in __page_mapcount
Date: Tue, 21 Dec 2021 18:40:15 +0000 [thread overview]
Message-ID: <YcIfj3nfuL0kzkFO@casper.infradead.org> (raw)
In-Reply-To: <CAHbLzkoU_giAFiOyhHZvxLT9Vie2-8TmQv_XLDpRxbec5r5weg@mail.gmail.com>
On Tue, Dec 21, 2021 at 10:24:27AM -0800, Yang Shi wrote:
> It seems the THP is split during smaps walk. The reproducer does call
> MADV_FREE on partial THP which may split the huge page.
>
> The below fix (untested) should be able to fix it.
Did you read the rest of the thread on this? If the page is being
migrated, we should still account it ... also, you've changed the
refcount, so this:
if (page_count(page) == 1) {
smaps_page_accumulate(mss, page, size, size << PSS_SHIFT, dirty,
locked, true);
return;
}
will never trigger.
next prev parent reply other threads:[~2021-12-21 18:40 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-31 0:53 [syzbot] kernel BUG in __page_mapcount syzbot
2021-06-07 17:27 ` split_huge_page_to_list() races with page_mapcount() on migration entry in smaps code? [was: Re: [syzbot] kernel BUG in __page_mapcount] Jann Horn
2021-06-07 18:03 ` Matthew Wilcox
2021-06-07 19:55 ` Jann Horn
2021-06-07 20:20 ` Matthew Wilcox
2021-06-07 20:49 ` Kirill A. Shutemov
2021-12-21 17:24 ` [syzbot] kernel BUG in __page_mapcount syzbot
2021-12-21 18:24 ` Yang Shi
2021-12-21 18:40 ` Matthew Wilcox [this message]
2021-12-21 19:07 ` Yang Shi
2021-12-22 1:42 ` Yang Shi
2022-01-05 19:05 ` Yang Shi
2022-01-11 23:14 ` Yang Shi
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