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 7DB2EC433EF for ; Thu, 21 Apr 2022 23:48:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1442797AbiDUXvr (ORCPT ); Thu, 21 Apr 2022 19:51:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49296 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1442774AbiDUXvj (ORCPT ); Thu, 21 Apr 2022 19:51:39 -0400 Received: from mail-qk1-x72f.google.com (mail-qk1-x72f.google.com [IPv6:2607:f8b0:4864:20::72f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0803535A9C; Thu, 21 Apr 2022 16:48:48 -0700 (PDT) Received: by mail-qk1-x72f.google.com with SMTP id j6so4752975qkp.9; Thu, 21 Apr 2022 16:48:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=eAsTyebn2Y4pYis3+WZXuPp8TzH7j4PwV2amK3FTGx8=; b=OOmnTYCAoQCRnBz8ZGchOn9i8U2hOeNPorJb87M3/pnKbf8r4wczk8AvZCUmTkG3mo xGWgYzNqWvYNey8z+NvJMhfgd1eg+nk1HGXrD25zDFPAUgk72Sa+LB7v6gfUO57Dvvme PUKAn+DVRz1g0IvpX6xC/IKenendQESOW7zlAWGHCNmpC2LVNI+AasWrGx5DlnqpEhuH GBs/HApRFPWfFJP9NkeR/a/P7ve/PSSxLMXaBDwU6FpPrKr9LlUltYvmFz5OWhNH5XKG T9QQFV9TmX/Y3Wc645Fpqp/Pqb4neHuqNYITdF61bPOzKiNfbMor6CQBRbRA0xBGNKNF hC3g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=eAsTyebn2Y4pYis3+WZXuPp8TzH7j4PwV2amK3FTGx8=; b=7DrS0+Z3mThWH+nQRLrzh6PdMedrZOjHURx5Rx5y4t2ET3SAO4ziFe2f0RYFM8VyG3 qSlYr3Ek70PnEv7cgcuvalIfWDas/Imv7z11eNgW3aXTuNfEdgEkBBnUbtf6o2ZKBgzM HfUWwSYuw4+3B0TzdKtMOk4RpbdXK3bciGSFtBu9SznZwgAR4CMTp+QP8F1RsN1Oyjqm I3D9zaX0QPY4J7MKfWwV1f7h1hSOS8ste2qB7vcgDSrmwZlGgrC/8fNwd66zkiHZ+Mj3 DwBBoMbKnq45riI/qt/FUgrfpipsty4jwwD7mCtllnKDvTLObl24kTtcpGmBbVEoYYpJ WHpg== X-Gm-Message-State: AOAM5332H2udxrushDNYsfFxAj7yTT6O/mNwdGb+3f0fkcC+q5SxYsme f8dCnWFLpHHLPt4DETQKnswMdWEZy1K5 X-Google-Smtp-Source: ABdhPJznB8ohPd49EoVGQUtsW/9dkOtNQzD1SuXVh4IxjthK+x2h94gl7xGMY9HG+LZtHfOVU1TYjw== X-Received: by 2002:a05:620a:4001:b0:69e:d9cf:d957 with SMTP id h1-20020a05620a400100b0069ed9cfd957mr1185369qko.678.1650584926675; Thu, 21 Apr 2022 16:48:46 -0700 (PDT) Received: from moria.home.lan (c-73-219-103-14.hsd1.vt.comcast.net. [73.219.103.14]) by smtp.gmail.com with ESMTPSA id a1-20020a05622a02c100b002f342ccc1c5sm287372qtx.72.2022.04.21.16.48.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Apr 2022 16:48:46 -0700 (PDT) From: Kent Overstreet To: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Cc: Kent Overstreet , roman.gushchin@linux.dev, hannes@cmpxchg.org Subject: [PATCH 2/4] mm: Add a .to_text() method for shrinkers Date: Thu, 21 Apr 2022 19:48:26 -0400 Message-Id: <20220421234837.3629927-3-kent.overstreet@gmail.com> X-Mailer: git-send-email 2.35.2 In-Reply-To: <20220421234837.3629927-1-kent.overstreet@gmail.com> References: <20220421234837.3629927-1-kent.overstreet@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org This adds a new callback method to shrinkers which they can use to describe anything relevant to memory reclaim about their internal state, for example object dirtyness. This uses the new printbufs to output to heap allocated strings, so that the .to_text() methods can be used both for messages logged to the console, and also sysfs/debugfs. This patch also adds shrinkers_to_text(), which reports on the top 10 shrinkers - by object count - in sorted order, to be used in OOM reporting. Signed-off-by: Kent Overstreet --- include/linux/shrinker.h | 5 +++ mm/vmscan.c | 75 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 80 insertions(+) diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h index 76fbf92b04..b5f411768b 100644 --- a/include/linux/shrinker.h +++ b/include/linux/shrinker.h @@ -2,6 +2,8 @@ #ifndef _LINUX_SHRINKER_H #define _LINUX_SHRINKER_H +struct printbuf; + /* * This struct is used to pass information from page reclaim to the shrinkers. * We consolidate the values for easier extension later. @@ -58,10 +60,12 @@ struct shrink_control { * @flags determine the shrinker abilities, like numa awareness */ struct shrinker { + char name[32]; unsigned long (*count_objects)(struct shrinker *, struct shrink_control *sc); unsigned long (*scan_objects)(struct shrinker *, struct shrink_control *sc); + void (*to_text)(struct printbuf *, struct shrinker *); long batch; /* reclaim batch size, 0 = default */ int seeks; /* seeks to recreate an obj */ @@ -94,4 +98,5 @@ extern int register_shrinker(struct shrinker *shrinker); extern void unregister_shrinker(struct shrinker *shrinker); extern void free_prealloced_shrinker(struct shrinker *shrinker); extern void synchronize_shrinkers(void); +void shrinkers_to_text(struct printbuf *); #endif diff --git a/mm/vmscan.c b/mm/vmscan.c index 59b14e0d69..09c483dfd3 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -50,6 +50,7 @@ #include #include #include +#include #include #include @@ -702,6 +703,80 @@ void synchronize_shrinkers(void) } EXPORT_SYMBOL(synchronize_shrinkers); +/** + * shrinkers_to_text - Report on shrinkers with highest usage + * + * This reports on the top 10 shrinkers, by object counts, in sorted order: + * intended to be used for OOM reporting. + */ +void shrinkers_to_text(struct printbuf *out) +{ + struct shrinker *shrinker; + struct shrinker_by_mem { + struct shrinker *shrinker; + unsigned long mem; + } shrinkers_by_mem[10]; + int i, nr = 0; + + if (!down_read_trylock(&shrinker_rwsem)) { + pr_buf(out, "(couldn't take shrinker lock)"); + return; + } + + list_for_each_entry(shrinker, &shrinker_list, list) { + struct shrink_control sc = { .gfp_mask = GFP_KERNEL, }; + unsigned long mem = shrinker->count_objects(shrinker, &sc); + + if (!mem || mem == SHRINK_STOP || mem == SHRINK_EMPTY) + continue; + + for (i = 0; i < nr; i++) + if (mem < shrinkers_by_mem[i].mem) + break; + + if (nr < ARRAY_SIZE(shrinkers_by_mem)) { + memmove(&shrinkers_by_mem[i + 1], + &shrinkers_by_mem[i], + sizeof(shrinkers_by_mem[0]) * (nr - i)); + nr++; + } else if (i) { + i--; + memmove(&shrinkers_by_mem[0], + &shrinkers_by_mem[1], + sizeof(shrinkers_by_mem[0]) * i); + } else { + continue; + } + + shrinkers_by_mem[i] = (struct shrinker_by_mem) { + .shrinker = shrinker, + .mem = mem, + }; + } + + for (i = nr - 1; i >= 0; --i) { + struct shrink_control sc = { .gfp_mask = GFP_KERNEL, }; + shrinker = shrinkers_by_mem[i].shrinker; + + if (shrinker->name[0]) + pr_buf(out, "%s", shrinker->name); + else + pr_buf(out, "%ps:", shrinker->scan_objects); + + pr_buf(out, " objects: %lu", shrinker->count_objects(shrinker, &sc)); + pr_newline(out); + + if (shrinker->to_text) { + pr_indent_push(out, 2); + shrinker->to_text(out, shrinker); + pr_indent_pop(out, 2); + pr_newline(out); + } + } + + up_read(&shrinker_rwsem); +} + #define SHRINK_BATCH 128 static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, -- 2.35.2