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Mon, 26 Oct 2026 13:53:12 -0400 (EDT) Date: Mon, 26 Oct 2026 17:53:11 +0000 From: Kiryl Shutsemau To: "David Hildenbrand (Arm)" Cc: Andrew Morton , Gregory Price , Zi Yan , Joshua Hahn , Rakie Kim , Ying Huang , Johannes Weiner , Vladimir Davydov , Michal Hocko , Hugh Dickins , Baolin Wang , Lukas Czerner , Carlos Maiolino , Christian Brauner , Jan Kara , Daniel Verkamp , Jeff Xu , Muchun Song , Oscar Salvador , David Stevens , "Matthew Wilcox (Oracle)" , William Kucharski , Chris Li , Kairui Song , Nhat Pham , Miaohe Lin , Naoya Horiguchi , linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH 14/16] mm/shmem: fix truncate loop after boundary swapin failure Message-ID: References: <20261026-fixes_shmem-v1-0-703206d5fa0c@kernel.org> <20261026-fixes_shmem-v1-14-703206d5fa0c@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261026-fixes_shmem-v1-14-703206d5fa0c@kernel.org> X-Stat-Signature: pa7a19mn75w91iqrhfzn6r19rwuzn1z8 X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 9CCD612000A X-Rspam-User: X-HE-Tag: 1793037195-306316 X-HE-Meta: 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 cAQ0Rbgm dElrb2xYscP1VQwkd81nMuoV9Pevu9BR9z4GdI6dFyzieTaPqBRY3W5nvxcs+8BCnTksHtghOiWDRdx0N9mUAc32ehztsnfvUAP6IDo/e0w0/TGlZTks6ahDAfLfrl04cAZ4YEd0cM4wowpEGOFvN2SHIUlv/JmXpM7NBlnlE0jZNlWxhFP2k9MEI+mJcQzN5B5a7E1qrKPKDXart5kHSzbdQfnkYewIhT4/5Ka0gwrGYwkTiDWpBv0w2MaZeSV4BgM9p/Sd+Zqlq+WEOpQaO68CoD5Qoki+DbRpxzKAXgEVqkEa22I0amdguLK4rTBzN+a+ePrLWe+xp1Z2uombdRUU8dFIINoWqlRCahjCcKSmO7mlzPi6AqJ53Br/6Hnnr9R1/j+BRGPSzMt/M3HIw4sFfmtOA3q4K6+LrLpb3NX3S+cFEgOkTBgBAMWuyan9l2/WJ9dcNxypgkXnt3kQAnW/7aVRb5JjyA20ydmyCZzw4OvDIO2zeHJySUinZhi2FtgHxXBla3Edxjh0CKBnCwM1kHS/oCuMGW0NGpOHfPmbom2G93ruVrfngn2pujvWsZiy/frezmFh4Q3Cwo1L5UAdCIqkn8ep0AH6LM06HjydIF+U= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Mon, Oct 26, 2026 at 10:40:47AM +0100, David Hildenbrand (Arm) wrote: > If swapping in a large entry at the new EOF fails, shmem_undo_range() > leaves the entry in place. Its final scan skips the entry, then restarts > from the same start index and finds it again. Truncation can loop forever > while holding i_rwsem. > > Advance start past the skipped entry so that a restarted scan can finish, > as we already do for folios that cannot be split. > > Note that this does not fix the missing zeroing when boundary swapin fails, > it merely prevents the endless loop. > > Fixes: 8a1968bd997f ("mm/shmem, swap: fix race of truncate and swap entry split") > Cc: stable@vger.kernel.org > Signed-off-by: David Hildenbrand (Arm) Okay, one more stop-gap: Acked-by: Kiryl Shutsemau (Meta) -- Kiryl Shutsemau / Kirill A. Shutemov