From patchwork Wed Apr 5 18:54:27 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yosry Ahmed X-Patchwork-Id: 13202373 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 A34FEC7619A for ; Wed, 5 Apr 2023 18:54:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230114AbjDESyn (ORCPT ); Wed, 5 Apr 2023 14:54:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49452 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234329AbjDESyi (ORCPT ); Wed, 5 Apr 2023 14:54:38 -0400 Received: from mail-pf1-x449.google.com (mail-pf1-x449.google.com [IPv6:2607:f8b0:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AB4E561B6 for ; Wed, 5 Apr 2023 11:54:33 -0700 (PDT) Received: by mail-pf1-x449.google.com with SMTP id a6-20020aa795a6000000b006262c174d64so16443433pfk.7 for ; Wed, 05 Apr 2023 11:54:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1680720873; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=4yIEsCxGxp+Goi3FcKFGmOxdWE8VaKQI4GXE/OXZVyU=; b=TF78184WybJytfdYm4GCjpWzSx4mUisBexI8bJfnyd6K4JeOX369L2ClHVn4Ys8I7V JV+y1m7UAB4SCcuHTJGFIgQF6+zPgKdblexEZW4hF8aKIUP946k53euPlWdSC0diJGII +4BQZqOlikwwOc1ffTqbrRHhEVpr3wXhWZ0WF/Lu4nUjgmKclpwmru3gluXbSweQuK7W C3JM5wV7WTynZX48f/Lp4lcdapj5Vg97KMACQe2OSnlckxh/DO5uCHLUHH1nrwiXFUnK JKlKgk5qWcBAj572MmVExUzKlzT1AeS/W+Ao4ZB3tIG21TaLoaVVgW0UNpmmTPc769jm okiw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680720873; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=4yIEsCxGxp+Goi3FcKFGmOxdWE8VaKQI4GXE/OXZVyU=; b=09EvEu5Y7d5/aNHL9WvDZ1d5bvOrX+xsBYVtQ1cjsrPj2CvNEegZVtjJucR0L6YUWU oeX/00p++2vQ7mscJssU4Mk2pa0ZEnBSybp6bWCliHAG128429dTUSW8yrwjeAZngKDF M0YsnePdRl6TS53NqWo5aYxZqAj634YD7afXBXEY+RloTYcAh1VnclAh6y8E8JNCsuxW jumot2tBYx4vreQLrx8DLwsJuRiABX6TRzrKrX+IN2zL9WPS7XDGu5Xxy4Rdyk2HtDqO cru7Qe+gIQvXwS/jmV+0HWrvXVhP1aEbq624+z4kJGANNvWhGYbP3MIWm4XAmwRynvN5 0vcQ== X-Gm-Message-State: AAQBX9fpYri0yZI3lfef+4PIN2T8wePqL3IujIAzO0ITLukCETH29U/D bNYFNHCXjKvy3soupkZsdtQGMA9r/uQg1zRY X-Google-Smtp-Source: AKy350acXJNtGWroYsn6aFMZG+1teLm2kBpgOPT0A7iZ6zD9rHb+p4s9om4KF91yo2bhBQ0j07DSjkYPZ7RoOPdC X-Received: from yosry.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:2327]) (user=yosryahmed job=sendgmr) by 2002:a05:6a00:2da6:b0:625:ccea:1627 with SMTP id fb38-20020a056a002da600b00625ccea1627mr3896876pfb.5.1680720873145; Wed, 05 Apr 2023 11:54:33 -0700 (PDT) Date: Wed, 5 Apr 2023 18:54:27 +0000 In-Reply-To: <20230405185427.1246289-1-yosryahmed@google.com> Mime-Version: 1.0 References: <20230405185427.1246289-1-yosryahmed@google.com> X-Mailer: git-send-email 2.40.0.348.gf938b09366-goog Message-ID: <20230405185427.1246289-3-yosryahmed@google.com> Subject: [PATCH v5 2/2] mm: vmscan: refactor reclaim_state helpers From: Yosry Ahmed To: Andrew Morton , Alexander Viro , "Darrick J. Wong" , Christoph Lameter , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, "Matthew Wilcox (Oracle)" , Miaohe Lin , David Hildenbrand , Johannes Weiner , Peter Xu , NeilBrown , Shakeel Butt , Michal Hocko , Yu Zhao , Dave Chinner Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, Yosry Ahmed Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org During reclaim, we keep track of pages reclaimed from other means than LRU-based reclaim through scan_control->reclaim_state->reclaimed_slab, which we stash a pointer to in current task_struct. However, we keep track of more than just reclaimed slab pages through this. We also use it for clean file pages dropped through pruned inodes, and xfs buffer pages freed. Rename reclaimed_slab to reclaimed, and add a helper function that wraps updating it through current, so that future changes to this logic are contained within mm/vmscan.c. Additionally, add a flush_reclaim_state() helper to wrap using reclaim_state->reclaimed to updated sc->nr_reclaimed, and use that helper to add an elaborate comment about why we only do the update for global reclaim. Finally, move set_task_reclaim_state() next to flush_reclaim_state() so that all reclaim_state helpers are in close proximity for easier readability. Signed-off-by: Yosry Ahmed --- fs/inode.c | 3 +- fs/xfs/xfs_buf.c | 3 +- include/linux/swap.h | 17 +++++++++- mm/slab.c | 3 +- mm/slob.c | 6 ++-- mm/slub.c | 5 ++- mm/vmscan.c | 75 ++++++++++++++++++++++++++++++++------------ 7 files changed, 78 insertions(+), 34 deletions(-) diff --git a/fs/inode.c b/fs/inode.c index 4558dc2f13557..e60fcc41faf17 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -864,8 +864,7 @@ static enum lru_status inode_lru_isolate(struct list_head *item, __count_vm_events(KSWAPD_INODESTEAL, reap); else __count_vm_events(PGINODESTEAL, reap); - if (current->reclaim_state) - current->reclaim_state->reclaimed_slab += reap; + mm_account_reclaimed_pages(reap); } iput(inode); spin_lock(lru_lock); diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index 54c774af6e1c6..15d1e5a7c2d34 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -286,8 +286,7 @@ xfs_buf_free_pages( if (bp->b_pages[i]) __free_page(bp->b_pages[i]); } - if (current->reclaim_state) - current->reclaim_state->reclaimed_slab += bp->b_page_count; + mm_account_reclaimed_pages(bp->b_page_count); if (bp->b_pages != bp->b_page_array) kmem_free(bp->b_pages); diff --git a/include/linux/swap.h b/include/linux/swap.h index 209a425739a9f..e131ac155fb95 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -153,13 +153,28 @@ union swap_header { * memory reclaim */ struct reclaim_state { - unsigned long reclaimed_slab; + /* pages reclaimed outside of LRU-based reclaim */ + unsigned long reclaimed; #ifdef CONFIG_LRU_GEN /* per-thread mm walk data */ struct lru_gen_mm_walk *mm_walk; #endif }; +/* + * mm_account_reclaimed_pages(): account reclaimed pages outside of LRU-based + * reclaim + * @pages: number of pages reclaimed + * + * If the current process is undergoing a reclaim operation, increment the + * number of reclaimed pages by @pages. + */ +static inline void mm_account_reclaimed_pages(unsigned long pages) +{ + if (current->reclaim_state) + current->reclaim_state->reclaimed += pages; +} + #ifdef __KERNEL__ struct address_space; diff --git a/mm/slab.c b/mm/slab.c index dabc2a671fc6f..64bf1de817b24 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -1392,8 +1392,7 @@ static void kmem_freepages(struct kmem_cache *cachep, struct slab *slab) smp_wmb(); __folio_clear_slab(folio); - if (current->reclaim_state) - current->reclaim_state->reclaimed_slab += 1 << order; + mm_account_reclaimed_pages(1 << order); unaccount_slab(slab, order, cachep); __free_pages(&folio->page, order); } diff --git a/mm/slob.c b/mm/slob.c index fe567fcfa3a39..79cc8680c973c 100644 --- a/mm/slob.c +++ b/mm/slob.c @@ -61,7 +61,7 @@ #include #include -#include /* struct reclaim_state */ +#include /* mm_account_reclaimed_pages() */ #include #include #include @@ -211,9 +211,7 @@ static void slob_free_pages(void *b, int order) { struct page *sp = virt_to_page(b); - if (current->reclaim_state) - current->reclaim_state->reclaimed_slab += 1 << order; - + mm_account_reclaimed_pages(1 << order); mod_node_page_state(page_pgdat(sp), NR_SLAB_UNRECLAIMABLE_B, -(PAGE_SIZE << order)); __free_pages(sp, order); diff --git a/mm/slub.c b/mm/slub.c index 39327e98fce34..7aa30eef82350 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -11,7 +11,7 @@ */ #include -#include /* struct reclaim_state */ +#include /* mm_account_reclaimed_pages() */ #include #include #include @@ -2063,8 +2063,7 @@ static void __free_slab(struct kmem_cache *s, struct slab *slab) /* Make the mapping reset visible before clearing the flag */ smp_wmb(); __folio_clear_slab(folio); - if (current->reclaim_state) - current->reclaim_state->reclaimed_slab += pages; + mm_account_reclaimed_pages(pages); unaccount_slab(slab, order, s); __free_pages(&folio->page, order); } diff --git a/mm/vmscan.c b/mm/vmscan.c index c82bd89f90364..049e39202e6ce 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -188,18 +188,6 @@ struct scan_control { */ int vm_swappiness = 60; -static void set_task_reclaim_state(struct task_struct *task, - struct reclaim_state *rs) -{ - /* Check for an overwrite */ - WARN_ON_ONCE(rs && task->reclaim_state); - - /* Check for the nulling of an already-nulled member */ - WARN_ON_ONCE(!rs && !task->reclaim_state); - - task->reclaim_state = rs; -} - LIST_HEAD(shrinker_list); DECLARE_RWSEM(shrinker_rwsem); @@ -511,6 +499,59 @@ static bool writeback_throttling_sane(struct scan_control *sc) } #endif +static void set_task_reclaim_state(struct task_struct *task, + struct reclaim_state *rs) +{ + /* Check for an overwrite */ + WARN_ON_ONCE(rs && task->reclaim_state); + + /* Check for the nulling of an already-nulled member */ + WARN_ON_ONCE(!rs && !task->reclaim_state); + + task->reclaim_state = rs; +} + +/* + * flush_reclaim_state(): add pages reclaimed outside of LRU-based reclaim to + * scan_control->nr_reclaimed. + */ +static void flush_reclaim_state(struct scan_control *sc, + struct reclaim_state *rs) +{ + /* + * Currently, reclaim_state->reclaimed includes three types of pages + * freed outside of vmscan: + * (1) Slab pages. + * (2) Clean file pages from pruned inodes. + * (3) XFS freed buffer pages. + * + * For all of these cases, we have no way of finding out whether these + * pages were related to the memcg under reclaim. For example, a freed + * slab page could have had only a single object charged to the memcg + * under reclaim. Also, populated inodes are not on shrinker LRUs + * anymore except on highmem systems. + * + * Instead of over-reporting the reclaimed pages in a memcg reclaim, + * only count such pages in global reclaim. This prevents unnecessary + * retries during memcg charging and false positive from proactive + * reclaim (memory.reclaim). + * + * For uncommon cases were the freed pages were actually significantly + * charged to the memcg under reclaim, and we end up under-reporting, it + * should be fine. The freed pages will be uncharged anyway, even if + * they are not reported properly, and we will be able to make forward + * progress in charging (which is usually in a retry loop). + * + * We can go one step further, and report the uncharged objcg pages in + * memcg reclaim, to make reporting more accurate and reduce + * under-reporting, but it's probably not worth the complexity for now. + */ + if (rs && global_reclaim(sc)) { + sc->nr_reclaimed += rs->reclaimed; + rs->reclaimed = 0; + } +} + static long xchg_nr_deferred(struct shrinker *shrinker, struct shrink_control *sc) { @@ -5346,10 +5387,7 @@ static int shrink_one(struct lruvec *lruvec, struct scan_control *sc) vmpressure(sc->gfp_mask, memcg, false, sc->nr_scanned - scanned, sc->nr_reclaimed - reclaimed); - if (global_reclaim(sc)) { - sc->nr_reclaimed += current->reclaim_state->reclaimed_slab; - current->reclaim_state->reclaimed_slab = 0; - } + flush_reclaim_state(sc, current->reclaim_state); return success ? MEMCG_LRU_YOUNG : 0; } @@ -6474,10 +6512,7 @@ static void shrink_node(pg_data_t *pgdat, struct scan_control *sc) shrink_node_memcgs(pgdat, sc); - if (reclaim_state && global_reclaim(sc)) { - sc->nr_reclaimed += reclaim_state->reclaimed_slab; - reclaim_state->reclaimed_slab = 0; - } + flush_reclaim_state(sc, reclaim_state); /* Record the subtree's reclaim efficiency */ if (!sc->proactive)