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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-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list 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> 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