From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794047898; b=FzrDNKGbG/jqBYgi9CVIsO12VcNqcHlKNEnEEh4dM2f5EQngqsayDfzKB5islMvL6inC QEPFNiEYtVpzyfHXyGtBUfg5DJqVfA7EpEM403mwqJpijHoZTXSZOeg9V20ur7c6pNccN L/a+Ps6uh8cttqmP/fcMDXXJHMKNk6BX1YYp3+MSmHoRqAj/qIxIfXgURV9OZ6wgDvTz5 F+9oC2cBQj8ARTihAHib1eHd5AKSTbNaQFuu2MCNTCHN7DUF/5dhrGkE6b5aop2fYDbO4 oq1Yv3Azf8XB50OBgbNMP5/nB3gg+Ot9pUwVtTpo+Q2FXT9BtTb6QuyrhAUCKxhfFAQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794047898; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=ypEp6OoVvOHYvMiaLHZdozFMsnjXIy2uQ91H8uZ2LeI=; b=uJ89YryCu+4vTPsFrh+Yd/mXPjNmrOa40NQvjmcY0rvar49gjXn7X2kfIknLG+MoIxpP diiiaDuuDk0nQHN6I1OjfpMnyODvZbE2MQqgt25cA7WiWugVzSqrDSLAIOmOyPrwRzwbm m5naiGpIQI0O9bm3KGqGXH7FMtBF2ufVh6EXzoQEUTaYYG+yUVCB9uLNZ8ciLAJ/bkhm6 LZXyfqnNvgxyi9qSfajKbUKCjE13mk4KEwWh4R9EWbDOIuqi0S2DWxqZoxUlEzBEwSPu9 6vPvSkPQkTZad62ZijTN9I/XxQu7W4BaGyazjclyE4DDJnEPMA4RA1BFH4FiquZIjFg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ggp3QEc+; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 66E0A606A32F for ; Sat, 7 Nov 2026 10:38:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=ggp3QEc+ Received: by smtp.kernel.org (Postfix) with ESMTPSA id B18551F0089F; Sat, 7 Nov 2026 10:38:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794047898; bh=ypEp6OoVvOHYvMiaLHZdozFMsnjXIy2uQ91H8uZ2LeI=; h=From:To:Cc:Subject:Date; b=ggp3QEc+UwDBkJibPC8ZpQS2NihJqZmJqNuNPMbO2dptkppdlATgCbj895ZSOk/Mh IkS0OX/Hv2qUj/3uHI/05gK8964uunAMlzPCxbbnwcq5t/VY+H2dCNtsQRSE9FhyD/ wvR8ToPPpLj5CF9kq4jwHnY8JLWlqBua9Z9aldBjQFOA6Qn4zAlQHZCY7lBBJIXBxR 05LNJR8uJ7cXg8pC4Sl+U57kTCc6KlbrELm2xykpcoLl1XCTt8US9z5GUE0b+js9yY ma4139vii6qcaHqzIQOr4FWgHnOL2VhRlN8P0RuK70lTXZpJgJ9V0aodSNpwHtFiyF LDIAEPoIMcp5w== From: Sasha Levin To: nick@karaolidis.com, chengzhihao1@huawei.com, jack@suse.cz, brauner@kernel.org Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] fs: don't lose inodes that another LRU walker is isolating" failed to apply to 6.6-stable tree Date: Sat, 7 Nov 2026 05:38:16 -0500 Message-ID: <20261107053816-failed-6.6-8dc4116041e2@kernel.org> X-Mailer: git-send-email 2.53.0 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=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 8dc4116041e2b377e5e1b62ba98b37636f9f3968 # git commit -s git send-email --to '' --in-reply-to '20261107053816-failed-6.6-8dc4116041e2@kernel.org' --subject-prefix 'PATCH 6.6.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 8dc4116041e2b377e5e1b62ba98b37636f9f3968 Mon Sep 17 00:00:00 2001 From: Nikolaos Karaolidis Date: Fri, 9 Oct 2026 14:24:31 +0000 Subject: [PATCH] fs: don't lose inodes that another LRU walker is isolating When inode_lru_isolate() finds an unused inode that still has page cache, it sets I_LRU_ISOLATING, drops i_lock and the list_lru lock, invalidates the page cache, clears the flag again and returns LRU_RETRY so that the restarted walk can free the inode. Another walker of the same list can reach the inode in that window. It sees a non-zero i_state and takes the inode off the LRU, as it would an inode that is in use. Page cache deletion requeues the inode once the mapping is shrinkable, so this is harmless if it happens before the last deletion. If it happens after, nothing puts the inode back: it stays in memory, unused, clean and without page cache, out of reach of the shrinker and of drop_caches, until it is looked up again or the filesystem is unmounted. Before commit 2a0629834cd8 ("vfs: Don't evict inode under the inode lru traversing context") the pin was an i_count reference, and the final iput() put the inode back on the LRU. Skip inodes that are being isolated and leave them to the walker that pinned them, which restarts its walk once it has unpinned them. The window is reached by any unused inode with page cache on CONFIG_HIGHMEM kernels, and otherwise by inodes whose page cache is a single shadow entry at index 0. On an i386 HIGHMEM guest, eight concurrent "echo 2 > /proc/sys/vm/drop_caches" over 2000 freshly read one-page ext4 files leave roughly 400 of the inodes off the LRU per round; on x86_64, with the files' pages first evicted through memory.reclaim, 3 to 4 per round. With this patch, none in either case. Fixes: 2a0629834cd8 ("vfs: Don't evict inode under the inode lru traversing context") Cc: stable@vger.kernel.org Signed-off-by: Nikolaos Karaolidis Link: https://patch.msgid.link/20261009142431.713875-1-nick@karaolidis.com Reviewed-by: Zhihao Cheng Reviewed-by: Jan Kara Signed-off-by: Christian Brauner (Amutable) --- fs/inode.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/inode.c b/fs/inode.c index d6353b8d1e634..f63535ee36291 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -941,6 +941,12 @@ static enum lru_status inode_lru_isolate(struct list_head *item, if (!spin_trylock(&inode->i_lock)) return LRU_SKIP; + /* Another walker is dropping its page cache, leave it to that one */ + if (inode_state_read(inode) & I_LRU_ISOLATING) { + spin_unlock(&inode->i_lock); + return LRU_SKIP; + } + /* * Inodes can get referenced, redirtied, or repopulated while * they're already on the LRU, and this can make them -- 2.53.0