From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8164FEB64D9 for ; Sun, 2 Jul 2023 19:43:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231886AbjGBTnY (ORCPT ); Sun, 2 Jul 2023 15:43:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53206 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231292AbjGBTms (ORCPT ); Sun, 2 Jul 2023 15:42:48 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C0D4D2D4A; Sun, 2 Jul 2023 12:41:49 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 9EFBF60D36; Sun, 2 Jul 2023 19:41:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CCDA4C433CA; Sun, 2 Jul 2023 19:41:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1688326877; bh=wiyEzbvdAoEVanuz3dTj+uFJ7dD+RlYWSclkQ4BUav4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BV9SeNc6k2D5/0LUsAkQ2w0mXcj6KU820847x3otBHs8c5VKDffVJt560Oh6bHD0m V2aeKo8HnByh8kkulY2bADAE24Uqe0FJan9Hz5ZVODa4dmIFO3Uimcg+Usy+QVfVA4 kRJdpEU29OpjBx07jatssr77W6kG0mUukFuJB3i6lkJ8QT/yjUP1dW8XPxjFxspWQv +qZRHZQnT4P1CxuWi/f2hK2tFoJ1j7uYyDXSNOpR7A9YswSsKIwHEwvL4zQlB1VQOs PXlWv93l1zKPYw9hdCgj6lg9ot1KkQJ/QzO1ZagQvvHphaZAU6ksq/+AV1C1+a8TE8 CJ58yV4Z7fVig== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sandeep Dhavale , Will Shiu , Gao Xiang , Gao Xiang , Alexandre Mergnat , Sasha Levin , chao@kernel.org, matthias.bgg@gmail.com, linux-erofs@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org Subject: [PATCH AUTOSEL 6.3 14/14] erofs: Fix detection of atomic context Date: Sun, 2 Jul 2023 15:40:53 -0400 Message-Id: <20230702194053.1777356-14-sashal@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230702194053.1777356-1-sashal@kernel.org> References: <20230702194053.1777356-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.3.11 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 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 d7add72a09437..77eb6a0c4853c 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -1455,7 +1455,7 @@ static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io, if (atomic_add_return(bios, &io->pending_bios)) return; /* Use (kthread_)work and sync decompression for atomic contexts only */ - if (in_atomic() || irqs_disabled()) { + if (!in_task() || irqs_disabled() || rcu_read_lock_any_held()) { #ifdef CONFIG_EROFS_FS_PCPU_KTHREAD struct kthread_worker *worker; -- 2.39.2