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=1794046278; b=lJejZN7bcDFcKF2HYyvPzxIKi2OqN/rmqTHFACEgkQVYqvhlzXW/eeorvnTdTxyCtiqe 89Lp6TwfUW76f9ZUUijYeqFBcZLC+nB59MkQmVpsUl/a8ZJMCXKSwIx7RPIrJz6OK5fbs BwWqEYrYgVgmr/sYsaAX8E/PiXljLZKArao8X6ksb8iwgmBXPY/IYk8okG4xabSVHrr/l UiCgAoPRniJocKHK0KOavUxVoWTHaqP8oYEj7IvDbwzLHxG95pUXNwd0qZXy5fg7/Z0yK 9JgziaNipIEqnk4UnKn/2dAhFUafeOfYOIFkuP39HOu5h0i7rTbIJAARSohblePArtQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794046278; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=cAi9SxhBTF1EMraayRCOyimuUj1KCwkhbYss6mZ7LTc=; b=k69pyOgJQ/8mohZA3tBh2gMOoPZOInBEaJUzS2JIzXWL+8husuYKiMJNy9q/br0nrA+d YTYT+CwmdlkDbzhOlNh45T/HvxEvz8D3HlnFw/EiyUwm83sGw6DJ8XkDXPAPASW1q6Gts XNN0J9isUOGjd5p1krALmvzW/ynNEzrdR2xmEofYadTdliPyoAbZthTmAuaXyRpJa/shQ euiyPwG5OS4vA0pqaddo3QJxMivdbv5T7/oWkAg/vS7ucTcI6MX44dI6CWd2waRz5Ap44 6EBIOy3+bBqmUwqVkBTSRT3/nUGLTd5uIPAyUOeynQ99Zqirw14wM+UFAdwdKalqspg== 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=IHjoyY4L; 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) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7C883606A33F for ; Sat, 7 Nov 2026 10:11:18 +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=IHjoyY4L Received: by smtp.kernel.org (Postfix) with ESMTPSA id F159F1F0089F; Sat, 7 Nov 2026 10:11:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794046278; bh=cAi9SxhBTF1EMraayRCOyimuUj1KCwkhbYss6mZ7LTc=; h=From:To:Cc:Subject:Date; b=IHjoyY4L4GXDbeLqoVxLlwaYU2mqzx5bX/1rcQdI/91hbjR4yRCBmYxXvZrx+S1TO 7HdFly1MXLhsYbAdmVAQKCmZp7Idbn1gw8kbeWOB4wbPMNDtmarNF8G3YYP4BMc1gV jcLAgjDLPQVgwlPxUJoUSVdZ4dzttdz4ZdJc3OFdazgFVMz1gL4d5Zlc+oFMinao6o mgo1sJQEvEORMtBKSv77obMk2Sc/5vCKLs3jx2+aVg9EMhBFbjBm3XJkff/PKGECEB JI1Ey8gXggpeTUNbCQBcB9PGFeKC0kpYRmx8xYyk8+IjRep7r4yAMs9KEnLzfSpRsu oaIArJY01DDMg== From: Sasha Levin To: chao@kernel.org, jaegeuk@kernel.org Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] f2fs: fix to use bio_in_atomic() in f2fs_read_end_io()" failed to apply to 6.18-stable tree Date: Sat, 7 Nov 2026 05:11:16 -0500 Message-ID: <20261107051116-failed-6.18-a605d5d71a6d@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 6.18-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-6.18.y git checkout FETCH_HEAD git cherry-pick -x a605d5d71a6d280c43c7ede9778dda63fb5c3f22 # git commit -s git send-email --to '' --in-reply-to '20261107051116-failed-6.18-a605d5d71a6d@kernel.org' --subject-prefix 'PATCH 6.18.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From a605d5d71a6d280c43c7ede9778dda63fb5c3f22 Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Sat, 10 Oct 2026 14:55:46 +0800 Subject: [PATCH] f2fs: fix to use bio_in_atomic() in f2fs_read_end_io() f2fs_read_end_io() uses "in_task() && !irqs_disabled()" to decide whether it is safe to sleep, the result is passed down as @in_task to: - f2fs_put_dic() -> f2fs_free_dic() -> f2fs_release_decomp_mem() -> vm_unmap_ram(), which may sleep. - f2fs_end_read_compressed_page() -> f2fs_cache_compressed_page() -> f2fs_grab_cache() -> f2fs_lock_cache(), which may sleep in wait_on_bit_lock(). However, the check still treats below task contexts as sleepable: - with spinlock held via spin_lock(), i.e. preempt count != 0 while irqs are enabled. - with BH disabled via local_bh_disable(). - inside an RCU read lock on kernels with CONFIG_PREEMPTION. - with any spinlock held on kernels without CONFIG_PREEMPT_COUNT. So the "sleeping function called from invalid context" issue fixed by commit 08a7efc5b02a ("f2fs: vm_unmap_ram() may be called from an invalid context") can still be triggered. The block layer provides bio_in_atomic() for exactly this purpose, it checks rcu_preempt_depth() and preemptible(), and conservatively returns true if CONFIG_PREEMPT_COUNT is disabled, let's use it instead. The difference is as below: old: intask = in_task() && !irqs_disabled() new: intask = !bio_in_atomic() Context | old intask | new intask -------------------------------------+----------------+---------------- Hard IRQ / softirq | false | false IRQs disabled | false | false spin_lock() held, IRQs enabled | true (wrong) | false BH disabled by local_bh_disable() | true (wrong) | false RCU read lock (CONFIG_PREEMPTION) | true (wrong) | false Spinlock held, w/o PREEMPT_COUNT | true (wrong) | false Note that on kernels without CONFIG_PREEMPT_COUNT, bio_in_atomic() always returns true, so dic freeing will always be offloaded to sbi->wq, and compressed pages will not be cached in f2fs_read_end_io(); this is the price of correctness, since there is no way to tell whether the current context can sleep. Cc: stable@kernel.org Fixes: 08a7efc5b02a ("f2fs: vm_unmap_ram() may be called from an invalid context") Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/data.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index ae3bde0767f3c..a8d39add5cbe0 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -271,7 +271,7 @@ static void f2fs_read_end_io(struct bio *bio) { struct f2fs_sb_info *sbi = F2FS_F_SB(bio_first_folio_all(bio)); struct bio_post_read_ctx *ctx; - bool intask = in_task() && !irqs_disabled(); + bool intask = !bio_in_atomic(); iostat_update_and_unbind_ctx(bio); ctx = bio->bi_private; -- 2.53.0