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[70.30.145.63]) by smtp.gmail.com with ESMTPSA id d65-20020a37b444000000b0073b3316bbd0sm2697192qkf.29.2023.02.21.14.18.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Feb 2023 14:18:23 -0800 (PST) Date: Tue, 21 Feb 2023 17:18:22 -0500 From: Peter Xu To: David Stevens Cc: linux-mm@kvack.org, Matthew Wilcox , Andrew Morton , "Kirill A . Shutemov" , Yang Shi , David Hildenbrand , Hugh Dickins , linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 3/3] mm/khugepaged: maintain page cache uptodate flag Message-ID: References: <20230217085439.2826375-1-stevensd@google.com> <20230217085439.2826375-4-stevensd@google.com> MIME-Version: 1.0 In-Reply-To: <20230217085439.2826375-4-stevensd@google.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspamd-Queue-Id: 694E21C000A X-Stat-Signature: tz5m1f1kpzmy5ttiknem6juwp3hdfpfp X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1677017908-566625 X-HE-Meta: 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 zm48fQr+ MZxqnrCbWYBXSezr2En1gPmudeqZ0JoDqsnpUENIo2zJRJ8icvmtUAjnOqDi+3o7Y5wOgihIVeVQz5g665FRSbld+IybrlH9C22RYxGHpUM7uEnlHLhfhtGF20EQAfcXn2fR9MyAVe15JCEiua/dcauH0tXvlhgVPhIi6lw5CVPtbOzSCDBHeARHZwL4KO7zg4IQNpdVE1eltmPx88YKS4X9t66rXj7uOhEjBEubXZbHKBieSJiVaZwYlXF2lHCDKubL0kRuA7z3zhCXNX+WHxWI2Eo0Czjp427CYRMfVSyAoE6/B8xC7Vu+Zgz0n0EqxdKJ2XmQXuX0Sivz9lGcaOP8reR0cCGxlszjD98kGaCF2TvMA37sdonQlJVfM/1SJ6EBVt/9mG4lJSOga7CxeStow7PAk0yIulEftAcHZQnwKu7o7WhVy/y/x3wGHGzB/DCCYwLVMb31+okc= 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: On Fri, Feb 17, 2023 at 05:54:39PM +0900, David Stevens wrote: > From: David Stevens > > Make sure that collapse_file doesn't interfere with checking the > uptodate flag in the page cache by only inserting hpage into the page > cache after it has been updated and marked uptodate. This is achieved by > simply not replacing present pages with hpage when iterating over them > target range. The present pages are already locked, so replacing the > with the locked hpage before the collapse is finalized is unnecessary. > > This fixes a race where folio_seek_hole_data would mistake hpage for > an fallocated but unwritten page. This race is visible to userspace via > data temporarily disappearing from SEEK_DATA/SEEK_HOLE. > > Fixes: f3f0e1d2150b ("khugepaged: add support of collapse for tmpfs/shmem pages") > Signed-off-by: David Stevens Per my knowledge, this one looks all correct too. Acked-by: Peter Xu So at least to me the whole set looks mostly good except patch 1 needs some confirmation. Thanks, -- Peter Xu