From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 676A24218AA; Thu, 23 Jul 2026 09:30:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784799055; cv=none; b=OVptxWecYJx08ekGTRT+Suga3aQ6vOCNfGfCDaJOmONL/O4ZHVcaJ/99Q7RfFRGNNWczPM/mgxSi9d2z3AiqQHO54nTfup7+Bzb2FnhVZEmBuD3XpLOvypQQ18Z9XRTfHvK8D7On/dNKyhvKOlh5C6yh595DPaN4Uwy5gnvu/34= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784799055; c=relaxed/simple; bh=3gUxBV2SQPcfcXwQIMQGNzjvePZYFdC4nDfoTiwbtLs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=qlE+jY+v2ijJdA/gXg4Y8pRVQe8yLJIQXnJVHpAtC2blHJDmGFzRXDUvRIJSZRaV3BXTSgtow/QWnlhBjHKrKlshhldHXqjXcjLaUZSNSuuZedRoIZ8dXKczL8P3swb8ftmJ40veECcoluzclfW5wCVO4NzPWoIXMgj2O6KZTlc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=QrnqwayX; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="QrnqwayX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8C5431F00A3A; Thu, 23 Jul 2026 09:30:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784799054; bh=wt67XsmwkQaRLRB+uB5Oux958CHUJdn7g1FXjqMrLvE=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=QrnqwayXlJrmoiZ0u1sB6zSrdj3atfwQyJsUJxcCMfxbHkmnZnv8ZLcdb4R9RpHBB FvQwOsQEGHluLfqGsSA6HgV0J27MWpP15ojOdmv22bKAWAx05QwuPO0y9xnXVC/WHN q3//A/panHvy6AOi4VBdoAtal6baa6STqbmSVoAwf0h5OCPvHSeDFREThUCsE/ZvIo GRywI7kYLfR2dIpMW0D1bgFxqn8o/tRVNyHirXRzQqQW2WEZhSTSeo1ZzAFdsEB1M7 dWISBVl056PFk58nrAodqbCurGD+PmvhYzGuRKAY9SLP9i2Qas1pEnOC9/sI05LaIe zt6dFVgml2+Hg== Message-ID: Date: Thu, 23 Jul 2026 11:30:49 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 12/13] mm/slab: add cache_ and slab_needs_objcg() helpers Content-Language: en-US To: Hao Li Cc: Harry Yoo , Suren Baghdasaryan , Shakeel Butt , Alexander Potapenko , Marco Elver , Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, cgroups@vger.kernel.org References: <20260720-b4-objext_split-v2-0-2fa7c6f60dbe@kernel.org> <20260720-b4-objext_split-v2-12-2fa7c6f60dbe@kernel.org> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/23/26 11:25, Hao Li wrote: > On Mon, Jul 20, 2026 at 04:16:26PM +0200, Vlastimil Babka (SUSE) wrote: >> @@ -359,6 +359,13 @@ struct kmem_cache *__kmem_cache_create_args(const char *name, >> goto out_unlock; >> } >> >> + /* >> + * For now we assume any cache can be used with __GFP_ACCOUNT and thus >> + * may need to store objcg pointers for objects >> + */ >> + if (!mem_cgroup_kmem_disabled()) >> + flags |= SLAB_MAY_ACCOUNT; > > if memcg itself is disabled via `cgroup_disable`, mem_cgroup_kmem_disabled() > still return false, so maybe we can use: Aha, but then shouldn't rather mem_cgroup_kmem_disabled() take that into account on its own? > if (!mem_cgroup_disabled() && !mem_cgroup_kmem_disabled()) > flags |= SLAB_MAY_ACCOUNT; > >> + >> /* Fail closed on bad usersize of useroffset values. */ >> if (!IS_ENABLED(CONFIG_HARDENED_USERCOPY) || >> WARN_ON(!args->usersize && args->useroffset) || >> @@ -984,11 +991,19 @@ new_kmalloc_cache(int idx, enum kmalloc_cache_type type) >> #endif >> >> /* >> - * If CONFIG_MEMCG is enabled, disable cache merging for >> - * KMALLOC_NORMAL caches. >> + * If memcg_kmem is enabled and this is a KMALLOC_NORMAL cache and not >> + * aliased with any other type, make sure it's never merged with any other >> + * cache. >> + * >> + * In other cases the kmalloc cache may end up being used for a >> + * __GFP_ACCOUNT allocation so mark it as such >> */ >> - if (IS_ENABLED(CONFIG_MEMCG) && (type == KMALLOC_NORMAL)) >> - flags |= SLAB_NO_MERGE; >> + if (!mem_cgroup_kmem_disabled()) { > > the same as above > > Others look good to me. > > Reviewed-by: Hao Li Thanks! > >> + if (type == KMALLOC_NORMAL && KMALLOC_RECLAIM != KMALLOC_NORMAL) >> + flags |= SLAB_NO_MERGE; >> + else >> + flags |= SLAB_MAY_ACCOUNT; >> + } >> >> if (minalign > ARCH_KMALLOC_MINALIGN) { >> aligned_size = ALIGN(aligned_size, minalign); >> diff --git a/mm/slub.c b/mm/slub.c >> index d78d3e50c877..30435e2509ea 100644 >> --- a/mm/slub.c >> +++ b/mm/slub.c >> @@ -2557,7 +2557,7 @@ bool memcg_slab_post_charge(void *p, gfp_t flags) >> * of slab_obj_exts being allocated from the same slab and thus the slab >> * becoming effectively unfreeable. >> */ >> - if (is_kmalloc_normal(s)) >> + if (!cache_needs_objcg(s)) >> return true; >> >> /* Ignore already charged objects. */ >> @@ -3435,6 +3435,10 @@ static struct slab *allocate_slab(struct kmem_cache *s, gfp_t flags, >> >> slab->objects = oo_objects(oo); >> >> +#ifdef CONFIG_64BIT >> + if (cache_needs_objcg(s)) >> + slab->obj_exts_needs_objcg = 1; >> +#endif >> slab->slab_cache = s; >> >> kasan_poison_slab(slab); >> >> -- >> 2.55.0 >> >