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=1794049502; b=lDQueI+oV4aU0GMCp4vEI03cSIFb7RSDd8S694fnWTRmtQwx7dC3Qwjawiq6jYmtFgpP lKbLNQvoOgzKKobH+w4tjN4DQIrl3RqBy+nyityrTK0CFQ8+6zuej2c8BjPLiVby19IxT /vobwjD+d7c/TF2uGXVRDINoIutRWNdY4KA0xF2L/wFTfGab407esb9fZIPVnkRN1Y/+j s/lpxWDMgYRsfwPcoS45d2ZSIcODsYjqbPO2sybK9GwDasnQniUVZGYttDF4tlO7cp+8c +3fGIflEaPd7YFCpW6EIARR+RBZdNGdz/ZOJt5TP5z//nM6J6qU0IbVzw8NUBKwrtxQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794049502; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=mxibyHZFt007KtnQlk9X+etA8jbYnMSnqotkEo5Q4/A=; b=MtVvVMnW4G54VB5kY2BbNipWs/rh5J9kqMEdrOTdtdSlcP5ERa28+TYaQgKUALwIjAAT k48Kpk4DplPFq3ZNPeNPfolppWievgVb8/w0EMCen3kWF3Crgb/cJ75lTyvRhTh3MBfsJ U31eF6TA+NoX+IR47BsqpQhI/kWCa8GIH8HDJ/75+4r/29J/TwR4HiwyKXtOln/ngjTYM j/RJ/VMGQOkvvIyyxIXsKcPpTP548V9G5idE414r9FecWn/XBSe5k82iFtZfY09tWav0D 6MddyQE5n8/X37GQiqwpGVMt8nk5ELA9bYvMKqYk1w8J8U/XNALu2cHFj20MVoI2m+A== 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=OYIPwDnk; 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 2B31E606A326 for ; Sat, 7 Nov 2026 11:05:02 +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=OYIPwDnk Received: by smtp.kernel.org (Postfix) with ESMTPSA id 431041F0089F; Sat, 7 Nov 2026 11:05:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794049502; bh=mxibyHZFt007KtnQlk9X+etA8jbYnMSnqotkEo5Q4/A=; h=From:To:Cc:Subject:Date; b=OYIPwDnkrH8FIz4ybHF+AxQJoqkG1916zkEkGoG7aLuYGE8Ej//aiV4iZOboOcsxE HQLT5v0zqTYJ18DllSc1XlmUotcDn9/hbTmPMj8Po13g6LJtFEqolAbHPVlvf131s+ NtJrcbKaie0BVFoQeVXgEvpbuYx9VkO5gVCy0zSU5LnaxWKmJFr2xI6MCeOtZArJGe g4HUFa3Kt55nWJK+cIhHBG3CXx+pfprKPVuzu/QL+hTDlahg+lwCCjjJo2Cym/0Uuu 4Qe1pAiyoXUFyU47Z1FgfWx2F1XKtOQJWAzYQwnZ1cNr4rbOgXYG+OorAo8nbhmNXv NPBivMaxi7W+g== From: Sasha Levin To: leitao@debian.org, akpm@linux-foundation.org, sj@kernel.org, baolin.wang@linux.alibaba.com, hughd@google.com, paulmck@kernel.org Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] mm/shmem: report RCU-tasks quiescent states while undoing a range" failed to apply to 5.15-stable tree Date: Sat, 7 Nov 2026 06:04:59 -0500 Message-ID: <20261107060459-failed-5.15-ebd1a08c1921@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 5.15-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-5.15.y git checkout FETCH_HEAD git cherry-pick -x ebd1a08c192109c83a87ddf42793ed6283180faf # git commit -s git send-email --to '' --in-reply-to '20261107060459-failed-5.15-ebd1a08c1921@kernel.org' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From ebd1a08c192109c83a87ddf42793ed6283180faf Mon Sep 17 00:00:00 2001 From: Breno Leitao Date: Fri, 18 Sep 2026 04:24:37 -0700 Subject: [PATCH] mm/shmem: report RCU-tasks quiescent states while undoing a range This shows up in the Meta fleet on ftruncate() of large tmpfs files: INFO: rcu_tasks detected stalls on tasks: 00000000752fd185: .. nvcsw: 59455/59455 holdout: 1 idle_cpu: -1/0 task:rocksdb:bottom state:R running task __folio_split find_get_entry find_get_entries truncate_inode_partial_folio shmem_undo_range shmem_setattr notify_change do_ftruncate __x64_sys_ftruncate do_syscall_64 shmem_undo_range() walks the whole of the requested range in folio_batch sized steps, twice, and its two cond_resched() calls are the only reschedule points in that walk. cond_resched() is not an RCU-tasks quiescent state. Use cond_resched_tasks_rcu_qs() at both points so the walk reports an RCU-tasks quiescent state as it proceeds. Link: https://lore.kernel.org/20260918-shmem-tasks-rcu-v1-1-79acf91a2569@debian.org Fixes: 8315f42295d2 ("rcu: Add call_rcu_tasks()") Signed-off-by: Breno Leitao Signed-off-by: Andrew Morton Reviewed-by: SJ Park Cc: Baolin Wang Cc: Hugh Dickins Cc: "Paul E . McKenney" Cc: --- mm/shmem.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index f33dbf5af2cb7..f2a36a1b53750 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1367,7 +1367,7 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, uoff_t lend, } folio_batch_remove_exceptionals(&fbatch); folio_batch_release(&fbatch); - cond_resched(); + cond_resched_tasks_rcu_qs(); } /* @@ -1408,7 +1408,7 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, uoff_t lend, index = start; while (index < end) { - cond_resched(); + cond_resched_tasks_rcu_qs(); if (!find_get_entries(mapping, &index, end - 1, &fbatch, indices)) { -- 2.53.0