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AJvYcCX9DOvPObMxrKslharmm+REsFTbL11/0DV4q5SrCH0Ctp8RG+jhxfSJQcENwAlMHfZCufyX2P5w@vger.kernel.org X-Gm-Message-State: AOJu0YxwxBp+EojWWM5aW3MIdkwHfDip1VgtCzNpG2RvQS6PhOPsTTHc g2JqXzUSv8wtEgtoDMz03F9nP/i8KelQJbQbWN8+1GY59OzukIaS+r0/cTjNxA== X-Google-Smtp-Source: AGHT+IEGOOT/8Hf+1rAAAGQHfgG5uBjGTgnPTvESY0/W1ruAvP96UeZmKwzbhDibddrutT5kRXi5Lg== X-Received: by 2002:a05:6a20:b68a:b0:1d2:e8f6:818 with SMTP id adf61e73a8af0-1d9a83d0a95mr45329316637.17.1730741438695; Mon, 04 Nov 2024 09:30:38 -0800 (PST) Received: from google.com ([2a00:79e0:2e28:6:e673:81cf:d338:f1bc]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-720bc2c7ef1sm7698084b3a.103.2024.11.04.09.30.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 Nov 2024 09:30:37 -0800 (PST) Date: Mon, 4 Nov 2024 10:30:29 -0700 From: Yu Zhao To: Shakeel Butt , Andrew Morton Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , Hugh Dickins , Yosry Ahmed , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, Meta kernel team Subject: Re: [PATCH v1 5/6] memcg-v1: no need for memcg locking for MGLRU Message-ID: References: <20241025012304.2473312-1-shakeel.butt@linux.dev> <20241025012304.2473312-6-shakeel.butt@linux.dev> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Sat, Oct 26, 2024 at 09:26:04AM -0600, Yu Zhao wrote: > On Sat, Oct 26, 2024 at 12:34 AM Shakeel Butt wrote: > > > > On Thu, Oct 24, 2024 at 06:23:02PM GMT, Shakeel Butt wrote: > > > While updating the generation of the folios, MGLRU requires that the > > > folio's memcg association remains stable. With the charge migration > > > deprecated, there is no need for MGLRU to acquire locks to keep the > > > folio and memcg association stable. > > > > > > Signed-off-by: Shakeel Butt > > > > Andrew, can you please apply the following fix to this patch after your > > unused fixup? > > Thanks! syzbot caught the following: WARNING: CPU: 0 PID: 85 at mm/vmscan.c:3140 folio_update_gen+0x23d/0x250 mm/vmscan.c:3140 ... Andrew, can you please fix this in place? Thank you. diff --git a/mm/vmscan.c b/mm/vmscan.c index ddaaff67642e..9a610dbff384 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3138,7 +3138,6 @@ static int folio_update_gen(struct folio *folio, int gen) unsigned long new_flags, old_flags = READ_ONCE(folio->flags); VM_WARN_ON_ONCE(gen >= MAX_NR_GENS); - VM_WARN_ON_ONCE(!rcu_read_lock_held()); do { /* lru_gen_del_folio() has isolated this page? */