From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1F9115111B5; Wed, 30 Sep 2026 16:37:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790786241; cv=none; b=X70EaZs43zjBJJkU8im1QRQDMRROB2LSRzjY0q6x8QG3E9qq1VTGOlbZ7/ZJX07TcuMuPzT5v9GvnkE7ip8uatDzSYB6JnEOPgrAoOISWJzQPU5PQ0IdN7OXhDeW0ITRtHHELQ3bUyPt2bZHP0m4jJwtBHDbn5EXVyKPxAmNcpY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790786241; c=relaxed/simple; bh=WyD8Wxq7mkRBao3yFDZZ4Gx7wfDWUHke/NGdcaNmdm8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NXFDwWwRsGsMF2fAvKpP3uhe3skg5CxZMChvg2iFTyHxFW0+Ej19P8qBLQJrF+CHkQoa/TeQ9KJ6PwoAAMqgssvCfAkuaPUQqRvgb1uFONzilqSyy7e/hxHsJHuGC6SmSh1m7GqouE7PCuAWlAtA5cRz7UDi4+hkUxffKcMmwbE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Og2YRueT; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Og2YRueT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 81EF71F000FF; Wed, 30 Sep 2026 16:37:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790786240; bh=0TaPLFbRL/XChmZ6oce33MosAf0AaJ3vkH3Ce7IBxHk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Og2YRueTgKzupeMwgocnDBtRZh/JAdR37QEd95xd4+Rfl0lVWgcLu2eRzRCim2iEJ wY8CdrEwEAHRKr+L5XqUcOS0uiphBSGKyVOO2g7QuZOAFCOzpi8wRoz66I4TQeCt+P +Q6bOVBj1Rlz7A7M3MntCp06dmt+5hNbepU0Wzss= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Will Shiu , Gao Xiang , Sandeep Dhavale , Gao Xiang , Alexandre Mergnat , Artem Dinaburg , Sasha Levin Subject: [PATCH 6.1 793/982] erofs: Fix detection of atomic context Date: Wed, 30 Sep 2026 17:25:29 +0200 Message-ID: <20260930152433.789347605@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152416.775402466@linuxfoundation.org> References: <20260930152416.775402466@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sandeep Dhavale [ Upstream commit 12d0a24afd9ea58e581ea64d64e066f2027b28d9 ] Current check for atomic context is not sufficient as z_erofs_decompressqueue_endio can be called under rcu lock from blk_mq_flush_plug_list(). See the stacktrace [1] In such case we should hand off the decompression work for async processing rather than trying to do sync decompression in current context. Patch fixes the detection by checking for rcu_read_lock_any_held() and while at it use more appropriate !in_task() check than in_atomic(). Background: Historically erofs would always schedule a kworker for decompression which would incur the scheduling cost regardless of the context. But z_erofs_decompressqueue_endio() may not always be in atomic context and we could actually benefit from doing the decompression in z_erofs_decompressqueue_endio() if we are in thread context, for example when running with dm-verity. This optimization was later added in patch [2] which has shown improvement in performance benchmarks. ============================================== [1] Problem stacktrace [name:core&]BUG: sleeping function called from invalid context at kernel/locking/mutex.c:291 [name:core&]in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 1615, name: CpuMonitorServi [name:core&]preempt_count: 0, expected: 0 [name:core&]RCU nest depth: 1, expected: 0 CPU: 7 PID: 1615 Comm: CpuMonitorServi Tainted: G S W OE 6.1.25-android14-5-maybe-dirty-mainline #1 Hardware name: MT6897 (DT) Call trace: dump_backtrace+0x108/0x15c show_stack+0x20/0x30 dump_stack_lvl+0x6c/0x8c dump_stack+0x20/0x48 __might_resched+0x1fc/0x308 __might_sleep+0x50/0x88 mutex_lock+0x2c/0x110 z_erofs_decompress_queue+0x11c/0xc10 z_erofs_decompress_kickoff+0x110/0x1a4 z_erofs_decompressqueue_endio+0x154/0x180 bio_endio+0x1b0/0x1d8 __dm_io_complete+0x22c/0x280 clone_endio+0xe4/0x280 bio_endio+0x1b0/0x1d8 blk_update_request+0x138/0x3a4 blk_mq_plug_issue_direct+0xd4/0x19c blk_mq_flush_plug_list+0x2b0/0x354 __blk_flush_plug+0x110/0x160 blk_finish_plug+0x30/0x4c read_pages+0x2fc/0x370 page_cache_ra_unbounded+0xa4/0x23c page_cache_ra_order+0x290/0x320 do_sync_mmap_readahead+0x108/0x2c0 filemap_fault+0x19c/0x52c __do_fault+0xc4/0x114 handle_mm_fault+0x5b4/0x1168 do_page_fault+0x338/0x4b4 do_translation_fault+0x40/0x60 do_mem_abort+0x60/0xc8 el0_da+0x4c/0xe0 el0t_64_sync_handler+0xd4/0xfc el0t_64_sync+0x1a0/0x1a4 [2] Link: https://lore.kernel.org/all/20210317035448.13921-1-huangjianan@oppo.com/ Reported-by: Will Shiu Suggested-by: Gao Xiang Signed-off-by: Sandeep Dhavale Reviewed-by: Gao Xiang Reviewed-by: Alexandre Mergnat Link: https://lore.kernel.org/r/20230621220848.3379029-1-dhavale@google.com Signed-off-by: Gao Xiang [ Backport to 6.1.y: the source change is unchanged; only its location in z_erofs_decompress_kickoff() differs. ] Assisted-by: LLM Signed-off-by: Artem Dinaburg Signed-off-by: Sasha Levin --- fs/erofs/zdata.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c index 66c323cbdd73e..49b7c77488415 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -1271,7 +1271,7 @@ static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io, if (atomic_add_return(bios, &io->pending_bios)) return; /* Use workqueue and sync decompression for atomic contexts only */ - if (in_atomic() || irqs_disabled()) { + if (!in_task() || irqs_disabled() || rcu_read_lock_any_held()) { queue_work(z_erofs_workqueue, &io->u.work); /* enable sync decompression for readahead */ if (sbi->opt.sync_decompress == EROFS_SYNC_DECOMPRESS_AUTO) -- 2.53.0