From patchwork Sun Dec 6 06:40:45 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yafang Shao X-Patchwork-Id: 11953685 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.5 required=3.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED,DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 95F8EC433FE for ; Sun, 6 Dec 2020 06:41:38 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2390322DFB for ; Sun, 6 Dec 2020 06:41:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2390322DFB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 99EA26B005D; Sun, 6 Dec 2020 01:41:37 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 94C646B0068; Sun, 6 Dec 2020 01:41:37 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 83C2B6B006C; Sun, 6 Dec 2020 01:41:37 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0053.hostedemail.com [216.40.44.53]) by kanga.kvack.org (Postfix) with ESMTP id 6BE006B005D for ; Sun, 6 Dec 2020 01:41:37 -0500 (EST) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 12DFE362C for ; Sun, 6 Dec 2020 06:41:37 +0000 (UTC) X-FDA: 77561911434.24.jam81_3e045d7273d3 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin24.hostedemail.com (Postfix) with ESMTP id EA1441A4A0 for ; Sun, 6 Dec 2020 06:41:36 +0000 (UTC) X-HE-Tag: jam81_3e045d7273d3 X-Filterd-Recvd-Size: 7498 Received: from mail-ot1-f68.google.com (mail-ot1-f68.google.com [209.85.210.68]) by imf30.hostedemail.com (Postfix) with ESMTP for ; Sun, 6 Dec 2020 06:41:36 +0000 (UTC) Received: by mail-ot1-f68.google.com with SMTP id d8so1580872otq.6 for ; Sat, 05 Dec 2020 22:41:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=m+1GohZiu08TBGb+QZ95Ht2UJWzVkthZE/EPME/oCwk=; b=iTmdW6lDzYxc/akRlnCX4vFlcQv4iNR1CUOefp5S4Btmh9kpjj/ogTxeulURwmLvFB ldMjrsCcOFGdLzkjgp5Wj8zogHJ16m65Cwc8CS5/RU+m3B+jCmMUdHMwgfCrCP2dt0pE LqZ1jMJnp464CZegBctCelsAuNqvIS0Pi/AUrpbz1imwFBM2PVEHcRwFy6XotuJAlxXj dtQ/NNzwy7mIocHcdq8A8qVLE9538iUVB0cfoPZD5gCXt7mhm5IwldLFoyKLehqw2EoO fmgxofIf2taEh0DjWvVq5hJIq+BAGxGO1ILEMoFZWNybcAXgKAWYL9CE9oXvb312uDKR dNoA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=m+1GohZiu08TBGb+QZ95Ht2UJWzVkthZE/EPME/oCwk=; b=jIYs6wtH+m7Iri/RtXDT+8L379z1VuKAaN1kOKLJf3RFN5tX4gcJXlBWJzwIqw3+VR Ey7LcdjpX07eG6Edhs6KbYLLOxg2uj80iYvqLwGsVJjddrXCGX7J7g9eOLPyNAdxJCDN zjzwNH3pjkHKe39aDu0gb/2ZF+tDWHUzzPunlPTRRSNwTwqBhi6n7pb1C33szKRldqfu HGTnlZ69Dfqu6+8ss2QzcZOtaje88LFkDlpAXh7FlL2Tg5Ca0eqQOKOmU5c9bclqxMbK vIk1RmeO5UKPexznTCX4w9eSIYvaC4OUy2iixGgE6HJesZ6VzD2+J1HK4K08spHTs7qH 6u5w== X-Gm-Message-State: AOAM532Go5huHurY+AtD6fydtIC0Abhye9Ztzu1xBrGDFR21OPLzbNvB YhdxvWH544ndqLXVnh7p2OU= X-Google-Smtp-Source: ABdhPJyaG+OZH5jroE971JONC6KbGt2J1QNHjJpwed0eyCQiNNQbHe8nYwl0PABcVt48pyD2EA234Q== X-Received: by 2002:a9d:6b8d:: with SMTP id b13mr8985231otq.168.1607236896025; Sat, 05 Dec 2020 22:41:36 -0800 (PST) Received: from localhost.localdomain ([122.225.203.131]) by smtp.gmail.com with ESMTPSA id y18sm1817553ooj.20.2020.12.05.22.41.24 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Sat, 05 Dec 2020 22:41:35 -0800 (PST) From: Yafang Shao To: darrick.wong@oracle.com, willy@infradead.org, hch@infradead.org, david@fromorbit.com, mhocko@kernel.org, 000akpm@linux-foundation.org, dhowells@redhat.com, jlayton@redhat.com Cc: linux-fsdevel@vger.kernel.org, linux-cachefs@redhat.com, linux-xfs@vger.kernel.org, linux-mm@kvack.org, Michal Hocko , Christoph Hellwig , Yafang Shao Subject: [PATCH v9 1/2] mm: Add become_kswapd and restore_kswapd Date: Sun, 6 Dec 2020 14:40:45 +0800 Message-Id: <20201206064046.2921-2-laoar.shao@gmail.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: <20201206064046.2921-1-laoar.shao@gmail.com> References: <20201206064046.2921-1-laoar.shao@gmail.com> MIME-Version: 1.0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: "Matthew Wilcox (Oracle)" Since XFS needs to pretend to be kswapd in some of its worker threads, create methods to save & restore kswapd state. Don't bother restoring kswapd state in kswapd -- the only time we reach this code is when we're exiting and the task_struct is about to be destroyed anyway. Cc: Dave Chinner Acked-by: Michal Hocko Reviewed-by: Darrick J. Wong Reviewed-by: Christoph Hellwig Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Yafang Shao --- fs/xfs/libxfs/xfs_btree.c | 14 ++++++++------ include/linux/sched/mm.h | 23 +++++++++++++++++++++++ mm/vmscan.c | 16 +--------------- 3 files changed, 32 insertions(+), 21 deletions(-) diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c index 2d25bab68764..a04a44238aab 100644 --- a/fs/xfs/libxfs/xfs_btree.c +++ b/fs/xfs/libxfs/xfs_btree.c @@ -2813,8 +2813,9 @@ xfs_btree_split_worker( { struct xfs_btree_split_args *args = container_of(work, struct xfs_btree_split_args, work); + bool is_kswapd = args->kswapd; unsigned long pflags; - unsigned long new_pflags = PF_MEMALLOC_NOFS; + int memalloc_nofs; /* * we are in a transaction context here, but may also be doing work @@ -2822,16 +2823,17 @@ xfs_btree_split_worker( * temporarily to ensure that we don't block waiting for memory reclaim * in any way. */ - if (args->kswapd) - new_pflags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; - - current_set_flags_nested(&pflags, new_pflags); + if (is_kswapd) + pflags = become_kswapd(); + memalloc_nofs = memalloc_nofs_save(); args->result = __xfs_btree_split(args->cur, args->level, args->ptrp, args->key, args->curp, args->stat); complete(args->done); - current_restore_flags_nested(&pflags, new_pflags); + memalloc_nofs_restore(memalloc_nofs); + if (is_kswapd) + restore_kswapd(pflags); } /* diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h index d5ece7a9a403..2faf03e79a1e 100644 --- a/include/linux/sched/mm.h +++ b/include/linux/sched/mm.h @@ -278,6 +278,29 @@ static inline void memalloc_nocma_restore(unsigned int flags) } #endif +/* + * Tell the memory management code that this thread is working on behalf + * of background memory reclaim (like kswapd). That means that it will + * get access to memory reserves should it need to allocate memory in + * order to make forward progress. With this great power comes great + * responsibility to not exhaust those reserves. + */ +#define KSWAPD_PF_FLAGS (PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD) + +static inline unsigned long become_kswapd(void) +{ + unsigned long flags = current->flags & KSWAPD_PF_FLAGS; + + current->flags |= KSWAPD_PF_FLAGS; + + return flags; +} + +static inline void restore_kswapd(unsigned long flags) +{ + current->flags &= ~(flags ^ KSWAPD_PF_FLAGS); +} + #ifdef CONFIG_MEMCG DECLARE_PER_CPU(struct mem_cgroup *, int_active_memcg); /** diff --git a/mm/vmscan.c b/mm/vmscan.c index 1b8f0e059767..77bc1dda75bf 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3869,19 +3869,7 @@ static int kswapd(void *p) if (!cpumask_empty(cpumask)) set_cpus_allowed_ptr(tsk, cpumask); - /* - * Tell the memory management that we're a "memory allocator", - * and that if we need more memory we should get access to it - * regardless (see "__alloc_pages()"). "kswapd" should - * never get caught in the normal page freeing logic. - * - * (Kswapd normally doesn't need memory anyway, but sometimes - * you need a small amount of memory in order to be able to - * page out something else, and this flag essentially protects - * us from recursively trying to free more memory as we're - * trying to free the first piece of memory in the first place). - */ - tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD; + become_kswapd(); set_freezable(); WRITE_ONCE(pgdat->kswapd_order, 0); @@ -3931,8 +3919,6 @@ static int kswapd(void *p) goto kswapd_try_sleep; } - tsk->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD); - return 0; }