From patchwork Sat Mar 15 17:49:27 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shakeel Butt X-Patchwork-Id: 14018169 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12E16C28B28 for ; Sat, 15 Mar 2025 17:50:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id CB49B280008; Sat, 15 Mar 2025 13:50:07 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C64C9280001; Sat, 15 Mar 2025 13:50:07 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B2D1F280008; Sat, 15 Mar 2025 13:50:07 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 924C0280001 for ; Sat, 15 Mar 2025 13:50:07 -0400 (EDT) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id E385A1CB138 for ; Sat, 15 Mar 2025 17:50:08 +0000 (UTC) X-FDA: 83224524096.21.AB489EB Received: from out-183.mta1.migadu.com (out-183.mta1.migadu.com [95.215.58.183]) by imf01.hostedemail.com (Postfix) with ESMTP id 0B32440003 for ; Sat, 15 Mar 2025 17:50:06 +0000 (UTC) Authentication-Results: imf01.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=kZK6wnzZ; spf=pass (imf01.hostedemail.com: domain of shakeel.butt@linux.dev designates 95.215.58.183 as permitted sender) smtp.mailfrom=shakeel.butt@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1742061007; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=tHvct7NUO2otKVtcPkikbwH9IxeqmMsC6tyfV+hMsCI=; b=UOUrqBMdbXPhRytFYq7k2ChDVzLp2dO0ovkJb1bdsBqPE9qylruhhI0NGvarKa2ZUgqvT9 bnLwuVaA+o44Ye/V76ad8Rb4DRwI7oifQkDL1/vw9yJCbu5uhQYdYJz++wEde1j8BeTGwz SjRbaxQIVebnTBDBLtahVyF2yAci4d0= ARC-Authentication-Results: i=1; imf01.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=kZK6wnzZ; spf=pass (imf01.hostedemail.com: domain of shakeel.butt@linux.dev designates 95.215.58.183 as permitted sender) smtp.mailfrom=shakeel.butt@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1742061007; a=rsa-sha256; cv=none; b=s2VH7L7wWnL8fidWyFOagWIFGGmqJiElbhXX2GXpuD5iTWMy0O/1wNdE0SIp/D5XSWjrkW eHcu3p1rK3P/4KbamD/hmSc2d6eUldYTwJamI7YtKzKKH+7CtYevK7uI0RruFoycpXhM+G wy49R1NsD4bNX946/tdGl7pWwaqscVg= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1742061003; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=tHvct7NUO2otKVtcPkikbwH9IxeqmMsC6tyfV+hMsCI=; b=kZK6wnzZBdB6KoWZYB2gbmXAmEglH6MpMFhomC5Kcno08qRkhhrz6/f/yhMsfRdCd8x3BY ZJHkxF4tenCzo+3OAxNHXlFxu7B6frqfODK2qZdld+O7uCsw0kDPPXntdcw72Ksl54uqxd 5fjRV2fVuE5qN1Q9kOdIaE6i/nHy4Gc= From: Shakeel Butt To: Andrew Morton Cc: Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Vlastimil Babka , Sebastian Andrzej Siewior , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Meta kernel team Subject: [PATCH 6/9] memcg: do obj_cgroup_put inside drain_obj_stock Date: Sat, 15 Mar 2025 10:49:27 -0700 Message-ID: <20250315174930.1769599-7-shakeel.butt@linux.dev> In-Reply-To: <20250315174930.1769599-1-shakeel.butt@linux.dev> References: <20250315174930.1769599-1-shakeel.butt@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Queue-Id: 0B32440003 X-Rspamd-Server: rspam08 X-Stat-Signature: jk5xrw97m8i36891r3xtxpcwcbt8f55z X-HE-Tag: 1742061006-572731 X-HE-Meta: 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 51Bi+hJ+ OkxRxenoM5S+X6Vu5M7coSsK7GLestcyd7Dqyym0Lh03qZ3JlgWvBzDN8hVraYDgZCgKCIc4Hh1wvc8Vjun/8k/IjrzynttRlxAiXCsg0AQJCU/5v7OQZlFQ5Sso2U68ETHeFhqX+3Qi8swXydeNIMmdcIHChMeqOp5zph0IxPmfyfKb09i2UrPUwyswnnxWpU3NauIe6Ejr+TVjjO59Fqj6IrQ== 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: List-Subscribe: List-Unsubscribe: Previously we could not call obj_cgroup_put() inside the local lock because on the put on the last reference, the release function obj_cgroup_release() may try to re-acquire the local lock. However that chain has been broken. Now simply do obj_cgroup_put() inside drain_obj_stock() instead of returning the old objcg. Signed-off-by: Shakeel Butt --- mm/memcontrol.c | 37 +++++++++++-------------------------- 1 file changed, 11 insertions(+), 26 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 83db180455a1..3c4de384b5a0 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1778,7 +1778,7 @@ static DEFINE_PER_CPU(struct memcg_stock_pcp, memcg_stock) = { }; static DEFINE_MUTEX(percpu_charge_mutex); -static struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock); +static void drain_obj_stock(struct memcg_stock_pcp *stock); static bool obj_stock_flush_required(struct memcg_stock_pcp *stock, struct mem_cgroup *root_memcg); @@ -1853,7 +1853,6 @@ static void drain_stock(struct memcg_stock_pcp *stock) static void drain_local_stock(struct work_struct *dummy) { struct memcg_stock_pcp *stock; - struct obj_cgroup *old = NULL; unsigned long flags; /* @@ -1864,12 +1863,11 @@ static void drain_local_stock(struct work_struct *dummy) localtry_lock_irqsave(&memcg_stock.stock_lock, flags); stock = this_cpu_ptr(&memcg_stock); - old = drain_obj_stock(stock); + drain_obj_stock(stock); drain_stock(stock); clear_bit(FLUSHING_CACHED_CHARGE, &stock->flags); localtry_unlock_irqrestore(&memcg_stock.stock_lock, flags); - obj_cgroup_put(old); } /* Should never be called with root_mem_cgroup. */ @@ -1951,18 +1949,16 @@ void drain_all_stock(struct mem_cgroup *root_memcg) static int memcg_hotplug_cpu_dead(unsigned int cpu) { struct memcg_stock_pcp *stock; - struct obj_cgroup *old; unsigned long flags; stock = &per_cpu(memcg_stock, cpu); /* drain_obj_stock requires stock_lock */ localtry_lock_irqsave(&memcg_stock.stock_lock, flags); - old = drain_obj_stock(stock); + drain_obj_stock(stock); localtry_unlock_irqrestore(&memcg_stock.stock_lock, flags); drain_stock(stock); - obj_cgroup_put(old); return 0; } @@ -2745,24 +2741,20 @@ void __memcg_kmem_uncharge_page(struct page *page, int order) } /* Replace the stock objcg with objcg, return the old objcg */ -static struct obj_cgroup *replace_stock_objcg(struct memcg_stock_pcp *stock, - struct obj_cgroup *objcg) +static void replace_stock_objcg(struct memcg_stock_pcp *stock, + struct obj_cgroup *objcg) { - struct obj_cgroup *old = NULL; - - old = drain_obj_stock(stock); + drain_obj_stock(stock); obj_cgroup_get(objcg); stock->nr_bytes = atomic_read(&objcg->nr_charged_bytes) ? atomic_xchg(&objcg->nr_charged_bytes, 0) : 0; WRITE_ONCE(stock->cached_objcg, objcg); - return old; } static void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, enum node_stat_item idx, int nr) { struct memcg_stock_pcp *stock; - struct obj_cgroup *old = NULL; unsigned long flags; int *bytes; @@ -2775,7 +2767,7 @@ static void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, * changes. */ if (READ_ONCE(stock->cached_objcg) != objcg) { - old = replace_stock_objcg(stock, objcg); + replace_stock_objcg(stock, objcg); stock->cached_pgdat = pgdat; } else if (stock->cached_pgdat != pgdat) { /* Flush the existing cached vmstat data */ @@ -2816,7 +2808,6 @@ static void mod_objcg_state(struct obj_cgroup *objcg, struct pglist_data *pgdat, __mod_objcg_mlstate(objcg, pgdat, idx, nr); localtry_unlock_irqrestore(&memcg_stock.stock_lock, flags); - obj_cgroup_put(old); } static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes) @@ -2838,12 +2829,12 @@ static bool consume_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes) return ret; } -static struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock) +static void drain_obj_stock(struct memcg_stock_pcp *stock) { struct obj_cgroup *old = READ_ONCE(stock->cached_objcg); if (!old) - return NULL; + return; if (stock->nr_bytes) { unsigned int nr_pages = stock->nr_bytes >> PAGE_SHIFT; @@ -2896,11 +2887,7 @@ static struct obj_cgroup *drain_obj_stock(struct memcg_stock_pcp *stock) } WRITE_ONCE(stock->cached_objcg, NULL); - /* - * The `old' objects needs to be released by the caller via - * obj_cgroup_put() outside of memcg_stock_pcp::stock_lock. - */ - return old; + obj_cgroup_put(old); } static bool obj_stock_flush_required(struct memcg_stock_pcp *stock, @@ -2922,7 +2909,6 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes, bool allow_uncharge) { struct memcg_stock_pcp *stock; - struct obj_cgroup *old = NULL; unsigned long flags; unsigned int nr_pages = 0; @@ -2930,7 +2916,7 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes, stock = this_cpu_ptr(&memcg_stock); if (READ_ONCE(stock->cached_objcg) != objcg) { /* reset if necessary */ - old = replace_stock_objcg(stock, objcg); + replace_stock_objcg(stock, objcg); allow_uncharge = true; /* Allow uncharge when objcg changes */ } stock->nr_bytes += nr_bytes; @@ -2941,7 +2927,6 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes, } localtry_unlock_irqrestore(&memcg_stock.stock_lock, flags); - obj_cgroup_put(old); if (nr_pages) obj_cgroup_uncharge_pages(objcg, nr_pages);