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bh=R9ohynNflqiL+Hy+OPCOUojcnVbfULl1TMrUnV9t3iA=; b=SmSBQJefG/oiPWBllQfQn9BZ9T Tz0HZIra0vmrCedn8z5pN9MiwBSJF/FAsTSyDjL+tPt58ZOwCYBUfdFcd08ZPsu3lsCeO5LFBgIPh u9s+j9FGu5EViFK+YL2DyanKmBGQNugBmZwD1orb78tx0xE8SQS6XKVwIt477PU1IBM6TlBZVp1yw U/aRNPVNPwSm7/hp6qsrvVetikTqqNXSYYhb5rbbjA70WZ+N76qsdMfuPjDeJc+2zviPqBM7ab0o3 tFGnXa2e32P38SbeMrn9rDo1ppJqWntthAmgcTUoCq8pUlDFrQT4YwgLulCC0qhWApGfVQsuQZIzc vbv3LU8A==; Received: from willy by casper.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1tnJSJ-0000000Fq1a-2Oyy; Wed, 26 Feb 2025 15:36:15 +0000 From: "Matthew Wilcox (Oracle)" To: Andrew Morton Cc: "Matthew Wilcox (Oracle)" , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: [PATCH] mm: Assert the folio is locked in folio_start_writeback() Date: Wed, 26 Feb 2025 15:36:12 +0000 Message-ID: <20250226153614.3774896-1-willy@infradead.org> X-Mailer: git-send-email 2.48.1 MIME-Version: 1.0 X-Rspam-User: X-Stat-Signature: c153jdzbzsqbhg9hmkqx3gpusi3redz7 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: A0928100028 X-HE-Tag: 1740584177-565456 X-HE-Meta: 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 pbL7IUHi pIdW/FT/PAcK9NccLiHN1G/SqjmD337QY2DCYw03j5+UYRRTJbrB8eoKpRJOKRGExdaxRyTcKfW0zEQTIIQ6TbBeONBjaZMqSPWKuZ5bTkXx59zIg8tFmADIEeOROQz5nEnuWwzut77uSjSnDCD67gq9HN/G8AaiQcmDeSfRkof1d38s6f7v1y6glZ5i2Xx5w9+zzKNvACfjzq7w2k1OCwCp+gpe9S46PsvNGZcCvl3qteMraCgLv/AvY0w88wFMPIyWHRKeXZa8tLe7cuehlJpaA6UoN7HfE8MB8CeZMdpZjRU1XZC9GkUjRHg== 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: List-Subscribe: List-Unsubscribe: The folio must be locked when we start writeback in order to prevent writeback from being started twice on the same folio. I don't expect this to catch any problems, but it should be good documentation. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: "Darrick J. Wong" --- mm/page-writeback.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index eb55ece39c56..8b325aa525eb 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -3109,6 +3109,7 @@ void __folio_start_writeback(struct folio *folio, bool keep_write) int access_ret; VM_BUG_ON_FOLIO(folio_test_writeback(folio), folio); + VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); if (mapping && mapping_use_writeback_tags(mapping)) { XA_STATE(xas, &mapping->i_pages, folio_index(folio));