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[91.12.103.241]) by smtp.gmail.com with ESMTPSA id b13sm10670911wrf.86.2021.08.16.01.04.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 16 Aug 2021 01:04:14 -0700 (PDT) To: qiang.zhang@windriver.com, vbabka@suse.cz, akpm@linux-foundation.org, sfr@canb.auug.org.au Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20210816074605.30336-1-qiang.zhang@windriver.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH] mm, slub: add cpus_read_lock/unlock() for slab_mem_going_offline_callback() Message-ID: Date: Mon, 16 Aug 2021 10:04:13 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210816074605.30336-1-qiang.zhang@windriver.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16.08.21 09:46, qiang.zhang@windriver.com wrote: > From: "Qiang.Zhang" > > The flush_all_cpus_locked() should be called with cpus_read_lock/unlock(), > ensure flush_cpu_slab() can be executed on schedule_on CPU. > > Fixes: 1c84f3c91640 ("mm, slub: fix memory and cpu hotplug related lock ordering issues") Which branch contains this commit? At least not linux.git or linux-next > Signed-off-by: Qiang.Zhang > --- > mm/slub.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/slub.c b/mm/slub.c > index 5543d57cb128..cf3f93abbd3e 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -4593,12 +4593,14 @@ static int slab_mem_going_offline_callback(void *arg) > { > struct kmem_cache *s; > > + cpus_read_lock(); > mutex_lock(&slab_mutex); > list_for_each_entry(s, &slab_caches, list) { > flush_all_cpus_locked(s); > __kmem_cache_do_shrink(s); > } > mutex_unlock(&slab_mutex); > + cpus_read_unlock(); > > return 0; > } > Memory notifiers are getting called from online_pages()/offline_pages(), where we call memory_notify(MEM_GOING_OFFLINE, &arg) under mem_hotplug_begin(). mem_hotplug_begin() does a cpus_read_lock(). How does this even work or against which branch is this? -- Thanks, David / dhildenb