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([2620:10d:c092:600::8a7e]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6004d50364dsm9100909a12.32.2025.05.21.09.39.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 21 May 2025 09:39:20 -0700 (PDT) Message-ID: <3d0a1483-3491-4c10-b19b-42bf0dace79e@gmail.com> Date: Wed, 21 May 2025 17:39:19 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: slub: do not warn when allocating slab obj extensions fails To: Suren Baghdasaryan Cc: Andrew Morton , hannes@cmpxchg.org, shakeel.butt@linux.dev, vlad.wing@gmail.com, linux-mm@kvack.org, kent.overstreet@linux.dev, cl@gentwo.org, rientjes@google.com, vbabka@suse.cz, roman.gushchin@linux.dev, harry.yoo@oracle.com, linux-kernel@vger.kernel.org, kernel-team@meta.com References: <20250521142521.3033264-1-usamaarif642@gmail.com> Content-Language: en-US From: Usama Arif In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 8484E4000B X-Stat-Signature: qqp5qqaimkxwzn1pjhgk8pxkjimdb6k9 X-Rspam-User: X-HE-Tag: 1747845562-648680 X-HE-Meta: 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 61BQYyZG 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 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: On 21/05/2025 17:29, Suren Baghdasaryan wrote: > On Wed, May 21, 2025 at 9:21 AM Usama Arif wrote: >> >> >> >> On 21/05/2025 17:02, Suren Baghdasaryan wrote: >>> On Wed, May 21, 2025 at 7:25 AM Usama Arif wrote: >>>> >>>> In memory bound systems, a large number of warnings for failing this >>>> allocation repeatedly may mask any real issues in the system >>>> during memory pressure being reported in dmesg. Failing this >>>> allocation is not indicative of a bug, so remove the warning. >>>> >>>> Signed-off-by: Usama Arif >>>> Reported-by: Vlad Poenaru >>>> Closes: https://lore.kernel.org/all/17fab2d6-5a74-4573-bcc3-b75951508f0a@gmail.com/ >>>> --- >>>> v1 -> v2: >>>> - remove the warning completely. We will have a way in the >>>> future to indicate that the mem alloc profile is inaccurate. >>>> --- >>>> mm/slub.c | 4 +--- >>>> 1 file changed, 1 insertion(+), 3 deletions(-) >>>> >>>> diff --git a/mm/slub.c b/mm/slub.c >>>> index dc9e729e1d26..06ab9a558b73 100644 >>>> --- a/mm/slub.c >>>> +++ b/mm/slub.c >>>> @@ -2102,9 +2102,7 @@ prepare_slab_obj_exts_hook(struct kmem_cache *s, gfp_t flags, void *p) >>>> >>>> slab = virt_to_slab(p); >>>> if (!slab_obj_exts(slab) && >>>> - WARN(alloc_slab_obj_exts(slab, s, flags, false), >>>> - "%s, %s: Failed to create slab extension vector!\n", >>>> - __func__, s->name)) >>>> + alloc_slab_obj_exts(slab, s, flags, false)) >>> >>> I thought we agreed to having pr_warn_once() here. Did I miss something? >>> >> >> I had [1] yesterday but I saw Johannes's mail [2] in and Harry mentioned in [3] that >> failing to allocate the extension vector can happen during normal operations. So I >> thought maybe there are more votes for removing it. >> >> I am ok with either pr_warn_once or removing it completely. > > I feel like we should have at least some indication that something > went wrong here. > >> >> I guess the question is, is it considered OK to fail here? > > Well, it's not ok but not catastrophic either, so warning seems > appropriate to me. > Ok, I will wait a couple of days incase someone has any objections and send https://lore.kernel.org/all/64b19c8f-e02e-490b-b987-9a996f36be21@gmail.com/ as v3. Thanks! >> >> [1] https://lore.kernel.org/all/64b19c8f-e02e-490b-b987-9a996f36be21@gmail.com/ >> [2] https://lore.kernel.org/all/20250520171814.GC773385@cmpxchg.org/ >> [3] https://lore.kernel.org/all/20250520171814.GC773385@cmpxchg.org/