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AJvYcCVYwT+XJU1iMB87IJ6NF+/QofdO9UlUAcfYq62H9/CfaFN6Wd+WIHl/YHDNQKKIFD/3yOYSn230FQ==@kvack.org X-Gm-Message-State: AOJu0YxANgAZDvfs+vRu9AInpGMeyeihjgAuqR4ymp1hZjRVOV1lnv0l jg/aTWc6BIpAEkpEZYm4l4VDZ8novsKv9WCaiZuOiKaXhTf9ZWV7pmQOvIpaj/CsHSjWGw/NXna gxbO7tqrMVkMvyyozF08Pqo0wBlQd8KGESKudxABS X-Gm-Gg: ASbGncvJnTpenLWR9nfAKK6ILUlGUtbBMV1We8za9qyAsh59PCoIsyq6dsT4Ui2RCJc +LnYsRqNvZ+wjVDycFFWtOiRzEC3yfTuNkXuB+H+K7WBRLhsVhAWM3AhGfbjUCbBDgXOZ8NC/7F ddLBqpjeK2fDx2ETn0MTU1iO8Z/sH5bi8X+7V3R4YDarvJ4m3lZaAxjSaDo+d/GI34jz5wLpUbE Q== X-Google-Smtp-Source: AGHT+IF4vRnCu/Qyj28nj92NPbeNkPOrDf8ATNK7jsHb4xuUnafzS15vPRBRNqqDt0Pzzkmkta6ELHPj9Y6uITNO0Mg= X-Received: by 2002:ac8:5781:0:b0:47e:a6ff:a215 with SMTP id d75a77b69052e-495864e985amr17325441cf.0.1747844987652; Wed, 21 May 2025 09:29:47 -0700 (PDT) MIME-Version: 1.0 References: <20250521142521.3033264-1-usamaarif642@gmail.com> In-Reply-To: From: Suren Baghdasaryan Date: Wed, 21 May 2025 09:29:35 -0700 X-Gm-Features: AX0GCFtQw9kHtYz6P7hsT3tw49iK_kxliqp14a0yxHWiABTp1Lzo6YbKTrXLPj8 Message-ID: Subject: Re: [PATCH] mm: slub: do not warn when allocating slab obj extensions fails To: Usama Arif 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: E291F1C000C X-Stat-Signature: a1mpcdi1g1xu6mh34m3f7wm3c4sskmuo X-HE-Tag: 1747844988-341404 X-HE-Meta: U2FsdGVkX19T7AOoGxakCwkb4Cvh4IEhpXXAStRlEl0VV8aJXZEJklknp9dTbU5mptaSRiktoV3cVcpJhdUPZELf0leOfblk4Mp6CdwJf5fAMgnJ90YXEPS+iydhL70nBaF0CeUK+jYS3DOi8+pA9Fv5IcEVKSDf1KYpeCVV/aR8pmZguIxpmN8BzGDSBInm93JW4Y+Y4Jl7lM6zQQxA7wahP+hWKByOIDS+XyupZ1J1HkneqCN056Eiqmt0emXkyMqdeNT1kdYjT5VAJLX9cOL1/sXn+CKKBasj5AGZHRE6rA8gbm9dphzzw6ycyb+AlHnqniKwBMEO94T6kHkTlMGwv1w+tgeGoe1QpGMaw0lBuK2mfc91iwDh7jT0846uYQDpCuynuJFcGB2L5KK7gUTX9sl25x2eCl6oU2fCj5Uu4FciVFRIz7NI5d2OOTFUN0V+JWmicrKHo3W7Dvkl86ailFz2C1OiWvKiBzbry7x4ZbyzTFm5TAqXjHrA4og0pZ3B1K1lvNaXigFUooT36Mgn9uc9bZocXZeJvz/zy0qhBI7cDJz+ksiWz0f6imDmZK2toh7RvnHhkHeIqkAH4kzOWxvyDCMp6CkVFHgNzH/3vUXFctpyJOa3HaX9vmZK+siTBl26DH7Y9we4oFOIPoP5IWVz8kdDfl4WvlBOM2bskdAsaE8fMkBkNvl3YRBmOonW/isvAbmw133fD9wGVKeWFzscqXvTNXPEd1lORjoJ4jKomBhH6CmF1NXOYykwamCFR/8v6F9WHvf4UEsmkmdV7KVuC37hB2QuFRbpQc9cdLFQkLlgStvnwfZZE35/epW/5BlN7fSmPUlRM2xs4sCPi94kRYdxZKFSwUeTyzrIdvigczFpaJ9Gut8cfp2oYlyjG+L8mxGaH/DuZa8TwWxmLST07UbPJLuEtYpjuCmk/zpwRuG1W0X6zDRanTqHzi/plo9NJwviMxN+fOE ITBmqYB4 Z2rNlDviw1EnhB6WT6sgEf0NApivBvSB7x9G7KyZ/xbQpSUxTN1rmrIKbAStC2yWq5JGSsnkqd1W4XuAnWXQ1RZcrKVj4f5vncS6YLAYoKlQ15FCuYya/LJynmnA2gtpSjTYy4mnchDw4Biuqb3FoqHYywfHbKs34eMMQpu4pG44bCR2HGkjZ/UgGQdT9cGYZtPcTCko+Zuvs3LWnp5CwSpYyXDxCRc5QIEiEGDlmvun9ofc9gqEs0gsTF+aPXuAYgA3ZcBxruH+0ENuZgjIE2W5SgS3iDGY/TbQvi8WKu1FTQdSvodVDNRa4TvokLFBuBE6zRx3UEQrmLZXtYrLLsaV1A+iu7Kci9MxfMoxzOJsAv3dtjgKJH/xthw== 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 Wed, May 21, 2025 at 9:21=E2=80=AFAM Usama Arif = wrote: > > > > On 21/05/2025 17:02, Suren Baghdasaryan wrote: > > On Wed, May 21, 2025 at 7:25=E2=80=AFAM 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-b75951508f= 0a@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 =3D 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 operati= ons. 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. > > [1] https://lore.kernel.org/all/64b19c8f-e02e-490b-b987-9a996f36be21@gmai= l.com/ > [2] https://lore.kernel.org/all/20250520171814.GC773385@cmpxchg.org/ > [3] https://lore.kernel.org/all/20250520171814.GC773385@cmpxchg.org/