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Thu, 9 Feb 2023 12:32:08 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id C4+tLsjn5GO/WQAAMHmgww (envelope-from ); Thu, 09 Feb 2023 12:32:08 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id 8147AA06E1; Thu, 9 Feb 2023 13:32:06 +0100 (CET) From: Jan Kara To: Cc: , , John Hubbard , David Howells , David Hildenbrand , Jan Kara Subject: [PATCH 1/5] mm: Do not reclaim private data from pinned page Date: Thu, 9 Feb 2023 13:31:53 +0100 Message-Id: <20230209123206.3548-1-jack@suse.cz> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230209121046.25360-1-jack@suse.cz> References: <20230209121046.25360-1-jack@suse.cz> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1241; i=jack@suse.cz; h=from:subject; bh=b7iWQ5YfsZfndhNXL2+FDh805OZp7+Jpf46CR42PtdM=; b=owEBbQGS/pANAwAIAZydqgc/ZEDZAcsmYgBj5Oe57YRO7wzPJ42BfBm4SCprTnrfRpao4H5EH7xY gEZK6vuJATMEAAEIAB0WIQSrWdEr1p4yirVVKBycnaoHP2RA2QUCY+TnuQAKCRCcnaoHP2RA2eMkCA DQnl4xH8vfdjSnutnULcqLL8Kq9ezcxTZO+bmhLzhnB7NAUjaACISpKijC086nmf0oiqZyqw90ylDw xpHWrFqToRVH1JrPM/P4aQEtCx8JGPO5utUYKImRrVa/2yLIWj1HVg7OAvgdhRpyt8U7C+nNQD1CPu NWNp5FUzSRyME02NaLU7Aji4OJTrN2fgIBFy1GX589g5nZBQDVMZI/NoY53I5pZk0d3h2yIwZJQt8L n2+UtOXc93bEka4NlcXi96gSH0OVyPtA5HivV03nc666TdEAf9DJC3TfyXp+QMB1Q+da4btV0UZS/j isheyYFhZduxQ4X6KGmoKYo7fny8/8 X-Developer-Key: i=jack@suse.cz; a=openpgp; fpr=93C6099A142276A28BBE35D815BC833443038D8C X-Rspamd-Queue-Id: 56A38100020 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: 7d4hes7pxsucgh7cz5e3iw4j99ud3bof X-HE-Tag: 1675945930-684223 X-HE-Meta: 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 3JsQ6Erc 8lTAFfYqXLdcFOxmlS6TWZNWZxzNQM0/soLc0m9wMtspe/Ue+vhD6uZ4LFcPwMAjFj31UitQRbo6TfL8V3dFXEsnlep1Ru7MsP4KIiUFTwxuxGZOLXelHfs38z3SzxDy1d7ueUbQaSunrmd0kvHHmVyuhkNTauKFqYD08wLHbJ25ydnZhAg/MSlD/7wjsLlIdtSlSh9yNtl92lGUUiGOp/D4L+4kclPwYyPzU4msNOWEXNNNCW7aPlV67uGIdwJKL+ESX 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: If the page is pinned, there's no point in trying to reclaim it. Furthermore if the page is from the page cache we don't want to reclaim fs-private data from the page because the pinning process may be writing to the page at any time and reclaiming fs private info on a dirty page can upset the filesystem (see link below). Link: https://lore.kernel.org/linux-mm/20180103100430.GE4911@quack2.suse.cz Signed-off-by: Jan Kara --- mm/vmscan.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/mm/vmscan.c b/mm/vmscan.c index bf3eedf0209c..ab3911a8b116 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1901,6 +1901,16 @@ static unsigned int shrink_folio_list(struct list_head *folio_list, } } + /* + * Folio is unmapped now so it cannot be newly pinned anymore. + * No point in trying to reclaim folio if it is pinned. + * Furthermore we don't want to reclaim underlying fs metadata + * if the folio is pinned and thus potentially modified by the + * pinning process is that may upset the filesystem. + */ + if (folio_maybe_dma_pinned(folio)) + goto activate_locked; + mapping = folio_mapping(folio); if (folio_test_dirty(folio)) { /*