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Thu, 17 Oct 2019 22:08:38 -0700 Received: by devbig006.ftw2.facebook.com (Postfix, from userid 4523) id 1100F62E3675; Thu, 17 Oct 2019 22:08:37 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Song Liu Smtp-Origin-Hostname: devbig006.ftw2.facebook.com To: , , CC: , , , , Song Liu , Johannes Weiner , Hugh Dickins Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH] mm,thp: recheck each page before collapsing file THP Date: Thu, 17 Oct 2019 22:08:32 -0700 Message-ID: <20191018050832.1251306-1-songliubraving@fb.com> X-Mailer: git-send-email 2.17.1 X-FB-Internal: Safe MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,1.0.8 definitions=2019-10-18_01:2019-10-17,2019-10-18 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 mlxlogscore=863 clxscore=1015 spamscore=0 impostorscore=0 priorityscore=1501 lowpriorityscore=0 suspectscore=0 malwarescore=0 adultscore=0 bulkscore=0 mlxscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1908290000 definitions=main-1910180048 X-FB-Internal: deliver X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: In collapse_file(), after locking the page, it is necessary to recheck that the page is up-to-date, clean, and pointing to the proper mapping. If any check fails, abort the collapse. Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") Cc: Kirill A. Shutemov Cc: Johannes Weiner Cc: Hugh Dickins Cc: William Kucharski Cc: Andrew Morton Signed-off-by: Song Liu Acked-by: Rik van Riel --- mm/khugepaged.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 0a1b4b484ac5..7da49b643c4d 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1619,6 +1619,14 @@ static void collapse_file(struct mm_struct *mm, result = SCAN_PAGE_LOCK; goto xa_locked; } + + /* double check the page is correct and clean */ + if (unlikely(!PageUptodate(page)) || + unlikely(PageDirty(page)) || + unlikely(page->mapping != mapping)) { + result = SCAN_FAIL; + goto out_unlock; + } } /*