From patchwork Fri Jul 14 06:45:06 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amir Goldstein X-Patchwork-Id: 13312999 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 37F6DEB64DA for ; Fri, 14 Jul 2023 06:46:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234522AbjGNGqU (ORCPT ); Fri, 14 Jul 2023 02:46:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36852 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233700AbjGNGqB (ORCPT ); Fri, 14 Jul 2023 02:46:01 -0400 Received: from mail-wm1-x32a.google.com (mail-wm1-x32a.google.com [IPv6:2a00:1450:4864:20::32a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 509F13AA8 for ; Thu, 13 Jul 2023 23:45:18 -0700 (PDT) Received: by mail-wm1-x32a.google.com with SMTP id 5b1f17b1804b1-3fbc5d5742eso15108115e9.3 for ; Thu, 13 Jul 2023 23:45:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1689317117; x=1691909117; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=hPSDIbaxTNh3TAqtA4XCx0bfvfZiTomjp6ixjsSsxD0=; b=bv/yKV2QJ6KV8SbknD5fNEKr1xx/VsE+9/itsFkNrrvuueCaiNjmsBbuA6hcCIs+M7 YSo6oLiToAZGQhZ2yR6i8ikuhl2qBVwie5rzUM0BA57JpSCifexgj9SSkwi95057tWgQ 989vpSqU62EkzJNPQvB8HNoIw4mXf0Dtyk/PO2egpNjCxwxq/HlO5vYtLdisZKgfoS3x bgzTE094yJZW2pVR12zyI3osI12zioic7hVbkPUJ0Ur4AqmyHu3+U2f3iu4/Mx7O/PAk miyAsFOC6pxAAT9Vru+TeWLFu3odakyfnaj2lux9ozUpOmzL8Wr2SH/T72vd3RugeHOm +AHQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689317117; x=1691909117; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=hPSDIbaxTNh3TAqtA4XCx0bfvfZiTomjp6ixjsSsxD0=; b=S3q1y+1MyBt59fOzKIoC3gNWdH9xxmkv3gYzfGqTWW7frj4pMcEzxcWfGPhq3ki45n RNTMx2BJEgraOo9Jst/EEHixzREjs6IE09WRZiOR7xR0Rsq97KPGSzs5yrZIwrHG9rdg g9Lhzj8f+tUOQYzmHkJok9sUP1v5r01BkeHOedJQsgE3gB7AlY98AwpimLd2P9nazWHy /byTDNOKp6JCfoxTeWB1AzEUcvhRbCnRBQn3WwRMxWxTX3pyojfGebn1RabvkOzny3/D D75dPeg6FjXvzYm11UCRPrrkJuxa82n7vecLu2umr1OK9dk7vBIrnRZ91l9HnkBkaPkn vLmg== X-Gm-Message-State: ABy/qLawunWqApxOOI5xa71LmlLJnRixGJYldq/bAN0cONyAxposSlx0 PWkj2zRe1hWZG+E5okheCJw= X-Google-Smtp-Source: APBJJlHwclFOABkAAgcMmXqdV9aAK7Mjax2S5r6Z5TpfCagTRY93xzw15kMTSOIfTHI90q2H6v6S/g== X-Received: by 2002:a05:600c:21c4:b0:3fb:b3f8:506b with SMTP id x4-20020a05600c21c400b003fbb3f8506bmr3215998wmj.24.1689317116747; Thu, 13 Jul 2023 23:45:16 -0700 (PDT) Received: from amir-ThinkPad-T480.lan ([5.29.249.86]) by smtp.gmail.com with ESMTPSA id 3-20020a05600c234300b003fc04d13242sm709574wmq.0.2023.07.13.23.45.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Jul 2023 23:45:16 -0700 (PDT) From: Amir Goldstein To: "Darrick J . Wong" Cc: Chandan Babu R , Leah Rumancik , Dave Chinner , Chris Dunlop , linux-xfs@vger.kernel.org, Dave Chinner Subject: [PATCH 6.1 CANDIDATE v2 1/4] xfs: explicitly specify cpu when forcing inodegc delayed work to run immediately Date: Fri, 14 Jul 2023 09:45:06 +0300 Message-Id: <20230714064509.1451122-2-amir73il@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230714064509.1451122-1-amir73il@gmail.com> References: <20230714064509.1451122-1-amir73il@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org From: "Darrick J. Wong" commit 03e0add80f4cf3f7393edb574eeb3a89a1db7758 upstream. I've been noticing odd racing behavior in the inodegc code that could only be explained by one cpu adding an inode to its inactivation llist at the same time that another cpu is processing that cpu's llist. Preemption is disabled between get/put_cpu_ptr, so the only explanation is scheduler mayhem. I inserted the following debug code into xfs_inodegc_worker (see the next patch): ASSERT(gc->cpu == smp_processor_id()); This assertion tripped during overnight tests on the arm64 machines, but curiously not on x86_64. I think we haven't observed any resource leaks here because the lockfree list code can handle simultaneous llist_add and llist_del_all functions operating on the same list. However, the whole point of having percpu inodegc lists is to take advantage of warm memory caches by inactivating inodes on the last processor to touch the inode. The incorrect scheduling seems to occur after an inodegc worker is subjected to mod_delayed_work(). This wraps mod_delayed_work_on with WORK_CPU_UNBOUND specified as the cpu number. Unbound allows for scheduling on any cpu, not necessarily the same one that scheduled the work. Because preemption is disabled for as long as we have the gc pointer, I think it's safe to use current_cpu() (aka smp_processor_id) to queue the delayed work item on the correct cpu. Fixes: 7cf2b0f9611b ("xfs: bound maximum wait time for inodegc work") Signed-off-by: Darrick J. Wong Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner Signed-off-by: Amir Goldstein --- fs/xfs/xfs_icache.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c index eae7427062cf..536885f8b8a8 100644 --- a/fs/xfs/xfs_icache.c +++ b/fs/xfs/xfs_icache.c @@ -2052,7 +2052,8 @@ xfs_inodegc_queue( queue_delay = 0; trace_xfs_inodegc_queue(mp, __return_address); - mod_delayed_work(mp->m_inodegc_wq, &gc->work, queue_delay); + mod_delayed_work_on(current_cpu(), mp->m_inodegc_wq, &gc->work, + queue_delay); put_cpu_ptr(gc); if (xfs_inodegc_want_flush_work(ip, items, shrinker_hits)) { @@ -2096,7 +2097,8 @@ xfs_inodegc_cpu_dead( if (xfs_is_inodegc_enabled(mp)) { trace_xfs_inodegc_queue(mp, __return_address); - mod_delayed_work(mp->m_inodegc_wq, &gc->work, 0); + mod_delayed_work_on(current_cpu(), mp->m_inodegc_wq, &gc->work, + 0); } put_cpu_ptr(gc); } From patchwork Fri Jul 14 06:45:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amir Goldstein X-Patchwork-Id: 13313000 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 3FF9DC001DC for ; Fri, 14 Jul 2023 06:46:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233778AbjGNGqV (ORCPT ); Fri, 14 Jul 2023 02:46:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37024 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234543AbjGNGqC (ORCPT ); Fri, 14 Jul 2023 02:46:02 -0400 Received: from mail-wm1-x332.google.com (mail-wm1-x332.google.com [IPv6:2a00:1450:4864:20::332]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 07AF7358E for ; Thu, 13 Jul 2023 23:45:20 -0700 (PDT) Received: by mail-wm1-x332.google.com with SMTP id 5b1f17b1804b1-3fbc244d307so14439505e9.1 for ; Thu, 13 Jul 2023 23:45:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1689317118; x=1691909118; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=Lq+6PEZbocUto3002utPHjzZHUQzj6s+6KUiweladO8=; b=cN1zjtyAjgTHsyjzUSl053xKuFMerWs3/V7VDN/0mGdBr8YFCz1mUqOl275lUNIxGL VNZgpbOCSUUIsUqSG8GlrtORpucbqQsWBYdK9JBN6qb2NTmIdF26D064u5HpZ+NpbaD/ nKwzvnvn8wg9PtUhkyU0Iv/ngtpIHwiGotrlIkToD++ocgHWeKkWLTywLo+O9XGtqFdt sbYcLZ0b2zd4mQY/n1ObvPRoI4LjOyTtq34c3je4MTNXvYXV8h0pAcD68kYsOZvx7942 iJTAtALood9Afx2lpp8w6oLEZvmGEzgdgM7tcBWPJ3/Mw/PaebNEzs2xOkRP+YH+HOAN UB/g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689317118; x=1691909118; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Lq+6PEZbocUto3002utPHjzZHUQzj6s+6KUiweladO8=; b=kdNrOzJgn54Xr1qRNoz6vyGLFAOhUqUOb7pmQg/EMaOIlL00wQ1gtTEvXunDjcP6QF NyddE+pGy5hlF3oDdVqs5RzlVGKNEi8R5zAmp2bS8vSKT7EpQv00DjxQgfyqVZNhR1OQ B8EQkcpyPRUsXTypDC1WwTnwQrHuest1rRts/rSWRp264IjpahtQRzF9jznmtTX/5KNv O0HUD72/nHX9CfcZDt+77j0BPR6U2+RsAlOuV6hrOpK03t9cC/TZIZdPakIOv+kjDdCq qgSl+/0VhrFO98deuIlNNxYXUB+twMQALtBdGwMKSKEJJgO3f5KXS8oGN3pZUA4a1lZR dKKQ== X-Gm-Message-State: ABy/qLYxZxGN02+itPWt8JR2QAq0A5+R9juvC3yPJx1sUwt7zjob+pz2 u0oisFxYZmW0BtBwQZIc6SU= X-Google-Smtp-Source: APBJJlEXhGK+mYO9EZ57iYfpgW1Qr/baoEVxxzhJAZMb1OM3EZU4EyaLZxrBNp8TGJAWxj9aIDd2dQ== X-Received: by 2002:a1c:f70a:0:b0:3fb:ff34:a846 with SMTP id v10-20020a1cf70a000000b003fbff34a846mr3314109wmh.22.1689317118081; Thu, 13 Jul 2023 23:45:18 -0700 (PDT) Received: from amir-ThinkPad-T480.lan ([5.29.249.86]) by smtp.gmail.com with ESMTPSA id 3-20020a05600c234300b003fc04d13242sm709574wmq.0.2023.07.13.23.45.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Jul 2023 23:45:17 -0700 (PDT) From: Amir Goldstein To: "Darrick J . Wong" Cc: Chandan Babu R , Leah Rumancik , Dave Chinner , Chris Dunlop , linux-xfs@vger.kernel.org, Dave Chinner Subject: [PATCH 6.1 CANDIDATE v2 2/4] xfs: check that per-cpu inodegc workers actually run on that cpu Date: Fri, 14 Jul 2023 09:45:07 +0300 Message-Id: <20230714064509.1451122-3-amir73il@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230714064509.1451122-1-amir73il@gmail.com> References: <20230714064509.1451122-1-amir73il@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org From: "Darrick J. Wong" commit b37c4c8339cd394ea6b8b415026603320a185651 upstream. Now that we've allegedly worked out the problem of the per-cpu inodegc workers being scheduled on the wrong cpu, let's put in a debugging knob to let us know if a worker ever gets mis-scheduled again. Signed-off-by: Darrick J. Wong Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner Signed-off-by: Amir Goldstein --- fs/xfs/xfs_icache.c | 2 ++ fs/xfs/xfs_mount.h | 3 +++ fs/xfs/xfs_super.c | 3 +++ 3 files changed, 8 insertions(+) diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c index 536885f8b8a8..7ce262dcabca 100644 --- a/fs/xfs/xfs_icache.c +++ b/fs/xfs/xfs_icache.c @@ -1848,6 +1848,8 @@ xfs_inodegc_worker( struct llist_node *node = llist_del_all(&gc->list); struct xfs_inode *ip, *n; + ASSERT(gc->cpu == smp_processor_id()); + WRITE_ONCE(gc->items, 0); if (!node) diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h index 8aca2cc173ac..69ddd5319634 100644 --- a/fs/xfs/xfs_mount.h +++ b/fs/xfs/xfs_mount.h @@ -66,6 +66,9 @@ struct xfs_inodegc { /* approximate count of inodes in the list */ unsigned int items; unsigned int shrinker_hits; +#if defined(DEBUG) || defined(XFS_WARN) + unsigned int cpu; +#endif }; /* diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c index ee4b429a2f2c..4b179526913f 100644 --- a/fs/xfs/xfs_super.c +++ b/fs/xfs/xfs_super.c @@ -1084,6 +1084,9 @@ xfs_inodegc_init_percpu( for_each_possible_cpu(cpu) { gc = per_cpu_ptr(mp->m_inodegc, cpu); +#if defined(DEBUG) || defined(XFS_WARN) + gc->cpu = cpu; +#endif init_llist_head(&gc->list); gc->items = 0; INIT_DELAYED_WORK(&gc->work, xfs_inodegc_worker); From patchwork Fri Jul 14 06:45:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Amir Goldstein X-Patchwork-Id: 13313001 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 45567EB64DA for ; Fri, 14 Jul 2023 06:46:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234877AbjGNGq0 (ORCPT ); Fri, 14 Jul 2023 02:46:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37296 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233932AbjGNGqE (ORCPT ); Fri, 14 Jul 2023 02:46:04 -0400 Received: from mail-wm1-x336.google.com (mail-wm1-x336.google.com [IPv6:2a00:1450:4864:20::336]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 455BA3AAF for ; Thu, 13 Jul 2023 23:45:21 -0700 (PDT) Received: by mail-wm1-x336.google.com with SMTP id 5b1f17b1804b1-3fbc63c2e84so13032735e9.3 for ; Thu, 13 Jul 2023 23:45:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1689317120; x=1691909120; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=AULk51Wj6WIrmGoDmUNSadsCc+FusPGzEe6kkkxXmZ4=; b=jXpII1jWguZC2oQkHM86gTibco6s05z0E/Jne9Gy8phVXlw4lh0jFUXdV3ZyFZLlUu Q6EBSfG/5TGKxJymXDPG+Rl50JV+pVJuAEILEP8OnIE+XDzD6BHwIABkTBMQQIKa0ES7 0cDaXAB4jzv/NsEJk+QJpxe3a6Ogf7MDk7TsRxgr99zDXwfAKeCPCyVybPQVTBesD/6Y OhB8YgM3GOnpMKt8yirHqvivMaio7FN/5ySbsk0sKeRiys+WFelOrc8tNz72uoTl4SHh PJcTLJ+7Y3OwZwp6/AX86IinST2Bycj2ZAJu9QXpHVTQw6p1vlgCNypACH4UxFf5k2BI ZOfA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689317120; x=1691909120; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=AULk51Wj6WIrmGoDmUNSadsCc+FusPGzEe6kkkxXmZ4=; b=A1LNSSglx0qPVrFZQKKH6SdwAW6fa+WdOqmY5OPyX8ouebn+ukkaPwSyyL3eRTdhGE eGQ/k3Asi9mvMqTdSjHcsfNz2c9vsxps8y1uET0uwRtO1PhzYPKrLJaz/zYOUcmXR9gh okUCEJIQRdSeO8VysKOvczN0am+3XC/VLkRthkjf2zhHcx8r9EIaHyoDRWbby5LCQ8e0 ykc0O/tT9Oqgj6ebmKvfqLpG73y4lTBoe3K+1MGFGjtblbLIj1EY26ql6k1CSWO0zrfG q7oox5QIjuVqBfuZ1ohG3L7uv3KHdeaIOYTZNew5w8yTAP6yXmonp9H9mot6XxcUlP+O oKug== X-Gm-Message-State: ABy/qLbAH29mqJccsPXU+gd91lYJ+POO90BkH+0CbHyv3x4VxYsNhgif 8YYJ7oELY8EX2ooNCfUXBhY= X-Google-Smtp-Source: APBJJlFgena6L06MGtwr+1s0SM+XoAbdT9VFYugWBqC3Qr1LPAKFNu9Igzf3cYMJV8RPTgwS68hrgQ== X-Received: by 2002:a7b:c454:0:b0:3f8:fac0:ad40 with SMTP id l20-20020a7bc454000000b003f8fac0ad40mr3732777wmi.29.1689317119529; Thu, 13 Jul 2023 23:45:19 -0700 (PDT) Received: from amir-ThinkPad-T480.lan ([5.29.249.86]) by smtp.gmail.com with ESMTPSA id 3-20020a05600c234300b003fc04d13242sm709574wmq.0.2023.07.13.23.45.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Jul 2023 23:45:19 -0700 (PDT) From: Amir Goldstein To: "Darrick J . Wong" Cc: Chandan Babu R , Leah Rumancik , Dave Chinner , Chris Dunlop , linux-xfs@vger.kernel.org, Dave Chinner Subject: [PATCH 6.1 CANDIDATE v2 3/4] xfs: disable reaping in fscounters scrub Date: Fri, 14 Jul 2023 09:45:08 +0300 Message-Id: <20230714064509.1451122-4-amir73il@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230714064509.1451122-1-amir73il@gmail.com> References: <20230714064509.1451122-1-amir73il@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org From: "Darrick J. Wong" commit 2d5f38a31980d7090f5bf91021488dc61a0ba8ee upstream. The fscounters scrub code doesn't work properly because it cannot quiesce updates to the percpu counters in the filesystem, hence it returns false corruption reports. This has been fixed properly in one of the online repair patchsets that are under review by replacing the xchk_disable_reaping calls with an exclusive filesystem freeze. Disabling background gc isn't sufficient to fix the problem. In other words, scrub doesn't need to call xfs_inodegc_stop, which is just as well since it wasn't correct to allow scrub to call xfs_inodegc_start when something else could be calling xfs_inodegc_stop (e.g. trying to freeze the filesystem). Neuter the scrubber for now, and remove the xchk_*_reaping functions. Signed-off-by: Darrick J. Wong Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner Signed-off-by: Amir Goldstein --- fs/xfs/scrub/common.c | 26 -------------------------- fs/xfs/scrub/common.h | 2 -- fs/xfs/scrub/fscounters.c | 13 ++++++------- fs/xfs/scrub/scrub.c | 2 -- fs/xfs/scrub/scrub.h | 1 - 5 files changed, 6 insertions(+), 38 deletions(-) diff --git a/fs/xfs/scrub/common.c b/fs/xfs/scrub/common.c index 9bbbf20f401b..e71449658ecc 100644 --- a/fs/xfs/scrub/common.c +++ b/fs/xfs/scrub/common.c @@ -865,29 +865,3 @@ xchk_ilock_inverted( } return -EDEADLOCK; } - -/* Pause background reaping of resources. */ -void -xchk_stop_reaping( - struct xfs_scrub *sc) -{ - sc->flags |= XCHK_REAPING_DISABLED; - xfs_blockgc_stop(sc->mp); - xfs_inodegc_stop(sc->mp); -} - -/* Restart background reaping of resources. */ -void -xchk_start_reaping( - struct xfs_scrub *sc) -{ - /* - * Readonly filesystems do not perform inactivation or speculative - * preallocation, so there's no need to restart the workers. - */ - if (!xfs_is_readonly(sc->mp)) { - xfs_inodegc_start(sc->mp); - xfs_blockgc_start(sc->mp); - } - sc->flags &= ~XCHK_REAPING_DISABLED; -} diff --git a/fs/xfs/scrub/common.h b/fs/xfs/scrub/common.h index 454145db10e7..2ca80102e704 100644 --- a/fs/xfs/scrub/common.h +++ b/fs/xfs/scrub/common.h @@ -148,7 +148,5 @@ static inline bool xchk_skip_xref(struct xfs_scrub_metadata *sm) int xchk_metadata_inode_forks(struct xfs_scrub *sc); int xchk_ilock_inverted(struct xfs_inode *ip, uint lock_mode); -void xchk_stop_reaping(struct xfs_scrub *sc); -void xchk_start_reaping(struct xfs_scrub *sc); #endif /* __XFS_SCRUB_COMMON_H__ */ diff --git a/fs/xfs/scrub/fscounters.c b/fs/xfs/scrub/fscounters.c index 6a6f8fe7f87c..88d6961e3886 100644 --- a/fs/xfs/scrub/fscounters.c +++ b/fs/xfs/scrub/fscounters.c @@ -128,13 +128,6 @@ xchk_setup_fscounters( if (error) return error; - /* - * Pause background reclaim while we're scrubbing to reduce the - * likelihood of background perturbations to the counters throwing off - * our calculations. - */ - xchk_stop_reaping(sc); - return xchk_trans_alloc(sc, 0); } @@ -353,6 +346,12 @@ xchk_fscounters( if (fdblocks > mp->m_sb.sb_dblocks) xchk_set_corrupt(sc); + /* + * XXX: We can't quiesce percpu counter updates, so exit early. + * This can be re-enabled when we gain exclusive freeze functionality. + */ + return 0; + /* * If ifree exceeds icount by more than the minimum variance then * something's probably wrong with the counters. diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c index 2e8e400f10a9..95132490fda5 100644 --- a/fs/xfs/scrub/scrub.c +++ b/fs/xfs/scrub/scrub.c @@ -171,8 +171,6 @@ xchk_teardown( } if (sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) mnt_drop_write_file(sc->file); - if (sc->flags & XCHK_REAPING_DISABLED) - xchk_start_reaping(sc); if (sc->buf) { kmem_free(sc->buf); sc->buf = NULL; diff --git a/fs/xfs/scrub/scrub.h b/fs/xfs/scrub/scrub.h index 3de5287e98d8..4cb32c27df10 100644 --- a/fs/xfs/scrub/scrub.h +++ b/fs/xfs/scrub/scrub.h @@ -88,7 +88,6 @@ struct xfs_scrub { /* XCHK state flags grow up from zero, XREP state flags grown down from 2^31 */ #define XCHK_TRY_HARDER (1 << 0) /* can't get resources, try again */ -#define XCHK_REAPING_DISABLED (1 << 2) /* background block reaping paused */ #define XREP_ALREADY_FIXED (1 << 31) /* checking our repair work */ /* Metadata scrubbers */ From patchwork Fri Jul 14 06:45:09 2023 Content-Type: text/plain; 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Wong" Cc: Chandan Babu R , Leah Rumancik , Dave Chinner , Chris Dunlop , linux-xfs@vger.kernel.org, Dave Chinner Subject: [PATCH 6.1 CANDIDATE v2 4/4] xfs: fix xfs_inodegc_stop racing with mod_delayed_work Date: Fri, 14 Jul 2023 09:45:09 +0300 Message-Id: <20230714064509.1451122-5-amir73il@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230714064509.1451122-1-amir73il@gmail.com> References: <20230714064509.1451122-1-amir73il@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org From: "Darrick J. Wong" commit 2254a7396a0ca6309854948ee1c0a33fa4268cec upstream. syzbot reported this warning from the faux inodegc shrinker that tries to kick off inodegc work: ------------[ cut here ]------------ WARNING: CPU: 1 PID: 102 at kernel/workqueue.c:1445 __queue_work+0xd44/0x1120 kernel/workqueue.c:1444 RIP: 0010:__queue_work+0xd44/0x1120 kernel/workqueue.c:1444 Call Trace: __queue_delayed_work+0x1c8/0x270 kernel/workqueue.c:1672 mod_delayed_work_on+0xe1/0x220 kernel/workqueue.c:1746 xfs_inodegc_shrinker_scan fs/xfs/xfs_icache.c:2212 [inline] xfs_inodegc_shrinker_scan+0x250/0x4f0 fs/xfs/xfs_icache.c:2191 do_shrink_slab+0x428/0xaa0 mm/vmscan.c:853 shrink_slab+0x175/0x660 mm/vmscan.c:1013 shrink_one+0x502/0x810 mm/vmscan.c:5343 shrink_many mm/vmscan.c:5394 [inline] lru_gen_shrink_node mm/vmscan.c:5511 [inline] shrink_node+0x2064/0x35f0 mm/vmscan.c:6459 kswapd_shrink_node mm/vmscan.c:7262 [inline] balance_pgdat+0xa02/0x1ac0 mm/vmscan.c:7452 kswapd+0x677/0xd60 mm/vmscan.c:7712 kthread+0x2e8/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308 This warning corresponds to this code in __queue_work: /* * For a draining wq, only works from the same workqueue are * allowed. The __WQ_DESTROYING helps to spot the issue that * queues a new work item to a wq after destroy_workqueue(wq). */ if (unlikely(wq->flags & (__WQ_DESTROYING | __WQ_DRAINING) && WARN_ON_ONCE(!is_chained_work(wq)))) return; For this to trip, we must have a thread draining the inodedgc workqueue and a second thread trying to queue inodegc work to that workqueue. This can happen if freezing or a ro remount race with reclaim poking our faux inodegc shrinker and another thread dropping an unlinked O_RDONLY file: Thread 0 Thread 1 Thread 2 xfs_inodegc_stop xfs_inodegc_shrinker_scan xfs_is_inodegc_enabled xfs_clear_inodegc_enabled xfs_inodegc_queue_all xfs_inodegc_queue xfs_is_inodegc_enabled drain_workqueue llist_empty mod_delayed_work_on(..., 0) __queue_work In other words, everything between the access to inodegc_enabled state and the decision to poke the inodegc workqueue requires some kind of coordination to avoid the WQ_DRAINING state. We could perhaps introduce a lock here, but we could also try to eliminate WQ_DRAINING from the picture. We could replace the drain_workqueue call with a loop that flushes the workqueue and queues workers as long as there is at least one inode present in the per-cpu inodegc llists. We've disabled inodegc at this point, so we know that the number of queued inodes will eventually hit zero as long as xfs_inodegc_start cannot reactivate the workers. There are four callers of xfs_inodegc_start. Three of them come from the VFS with s_umount held: filesystem thawing, failed filesystem freezing, and the rw remount transition. The fourth caller is mounting rw (no remount or freezing possible). There are three callers ofs xfs_inodegc_stop. One is unmounting (no remount or thaw possible). Two of them come from the VFS with s_umount held: fs freezing and ro remount transition. Hence, it is correct to replace the drain_workqueue call with a loop that drains the inodegc llists. Fixes: 6191cf3ad59f ("xfs: flush inodegc workqueue tasks before cancel") Signed-off-by: Darrick J. Wong Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner Signed-off-by: Amir Goldstein --- fs/xfs/xfs_icache.c | 32 +++++++++++++++++++++++++++----- 1 file changed, 27 insertions(+), 5 deletions(-) diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c index 7ce262dcabca..d884cba1d707 100644 --- a/fs/xfs/xfs_icache.c +++ b/fs/xfs/xfs_icache.c @@ -431,18 +431,23 @@ xfs_iget_check_free_state( } /* Make all pending inactivation work start immediately. */ -static void +static bool xfs_inodegc_queue_all( struct xfs_mount *mp) { struct xfs_inodegc *gc; int cpu; + bool ret = false; for_each_online_cpu(cpu) { gc = per_cpu_ptr(mp->m_inodegc, cpu); - if (!llist_empty(&gc->list)) + if (!llist_empty(&gc->list)) { mod_delayed_work_on(cpu, mp->m_inodegc_wq, &gc->work, 0); + ret = true; + } } + + return ret; } /* @@ -1894,24 +1899,41 @@ xfs_inodegc_flush( /* * Flush all the pending work and then disable the inode inactivation background - * workers and wait for them to stop. + * workers and wait for them to stop. Caller must hold sb->s_umount to + * coordinate changes in the inodegc_enabled state. */ void xfs_inodegc_stop( struct xfs_mount *mp) { + bool rerun; + if (!xfs_clear_inodegc_enabled(mp)) return; + /* + * Drain all pending inodegc work, including inodes that could be + * queued by racing xfs_inodegc_queue or xfs_inodegc_shrinker_scan + * threads that sample the inodegc state just prior to us clearing it. + * The inodegc flag state prevents new threads from queuing more + * inodes, so we queue pending work items and flush the workqueue until + * all inodegc lists are empty. IOWs, we cannot use drain_workqueue + * here because it does not allow other unserialized mechanisms to + * reschedule inodegc work while this draining is in progress. + */ xfs_inodegc_queue_all(mp); - drain_workqueue(mp->m_inodegc_wq); + do { + flush_workqueue(mp->m_inodegc_wq); + rerun = xfs_inodegc_queue_all(mp); + } while (rerun); trace_xfs_inodegc_stop(mp, __return_address); } /* * Enable the inode inactivation background workers and schedule deferred inode - * inactivation work if there is any. + * inactivation work if there is any. Caller must hold sb->s_umount to + * coordinate changes in the inodegc_enabled state. */ void xfs_inodegc_start(