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 AB316411690; Tue, 21 Jul 2026 09:23:18 +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=1784625799; cv=none; b=fT5sMpNfu0hiUJqOrrfCrXQ+o157mmYN6AEpP/TjyyfSZTDd2YqXiZmvYN7NSKPjxKfaFmXpraZfLsg3GXVPmLX7o4dPCtlcRcWfL2E201k9oD4dritstfIqe5kQXQ9AYXtrO1zktqRgqj6OaORlHnEG8zwouSsOuI5Kq59GZxw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784625799; c=relaxed/simple; bh=bicqtGjQss9r404M6Na8dkSPa5rfX/N1tPNJLRu1sVs=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=RIeu/ligLu9X6t0sETvGp/nd2udEHoHHh6S1AHFEf7jEs2b/G9yOzZmKHcTBkbKBnTFG/eiUvJvPNwwwpw/3eoMDGv4+Nn+Ij1bXuVUxIjW3nhWDbtm1tSF47ArieEwmb4IIJDIIqkb/k30fY7lXjpM1gfnoiXZhpMrHNidRHs0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bI8/+VZ3; 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="bI8/+VZ3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9C25D1F00A3A; Tue, 21 Jul 2026 09:23:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784625798; bh=AATOw6YQ1sIpEbY+KeCTcTRiayqedE1/R6uTPVHB/gA=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=bI8/+VZ3mWyeB/E6Z3Q4ZSlnsRIcq16tiBSwfW6RbFFtGhrAHc4o4lCmnQAmY2HIc 6CBwSeN6fhTSyOvnVZH5YtxDkcORiiRoYOezxfCJK174jOoviLo3hYOd/1kwPzM1mc StD/fVAF/hnr3pvXdmbSy1cXLdPEEb6B6RWIeV5i5M7euryuNXUayTYfMhsyvHhlay chBgHTbl+wtJoPdtSZLJ2b3E7AVXZkbgY70pk4KYFDMqTg2/bomwr6vQP4AamD1DaE HykGvfuiQfro/3Vil7c72LtnEZI0Zx1eYHZ4h0mGfRnXC30fcduPAile8zfTnZmrhm amZNRn03nw5aQ== Message-ID: <392e6115-cc92-4c33-bbbe-1211c279a518@kernel.org> Date: Tue, 21 Jul 2026 11:23:14 +0200 Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 02/13] mm/slub: skip handle_failed_objexts_alloc() with profiling disabled Content-Language: en-US To: Harry Yoo , Suren Baghdasaryan Cc: Hao Li , 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-v2-2-2fa7c6f60dbe@kernel.org> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 7/21/26 07:51, Harry Yoo wrote: > > > On 7/20/26 11:16 PM, Vlastimil Babka (SUSE) wrote: >> The function might get called with memory allocation profiling disabled, >> when the obj_ext array is allocated for objcg pointers only. The >> handling is however unnecessary in that case, so skip it. >> >> This would otherwise become a real bug later, as pointed out by sashiko. >> For now it's just an optimization. >> >> Link: https://sashiko.dev/#/patchset/20260715-b4-objext_split-v1-0-9a49c4ccf4c3@kernel.org?part=10 >> Signed-off-by: Vlastimil Babka (SUSE) >> --- >> mm/slub.c | 7 ++++--- >> 1 file changed, 4 insertions(+), 3 deletions(-) >> >> diff --git a/mm/slub.c b/mm/slub.c >> index 76acb78f2655..95fa6fbad11a 100644 >> --- a/mm/slub.c >> +++ b/mm/slub.c >> @@ -2101,15 +2101,16 @@ static inline bool mark_failed_objexts_alloc(struct slab *slab) >> static inline void handle_failed_objexts_alloc(unsigned long obj_exts, >> struct slabobj_ext *vec, unsigned int objects) >> { >> + if (!mem_alloc_profiling_enabled()) >> + return; > > This looks racy. Indeed, not sure how I convinced myself it's ok. > Can we instead do this later in the series depending on > slab_obj_ext_has_codetag_key's value? Yeah. >> /* >> * If vector previously failed to allocate then we have live >> * objects with no tag reference. Mark all references in this >> * vector as empty to avoid warnings later on. >> */ >> if (obj_exts == OBJEXTS_ALLOC_FAIL) { >> - unsigned int i; >> - >> - for (i = 0; i < objects; i++) >> + for (unsigned int i = 0; i < objects; i++) >> set_codetag_empty(&vec[i].ref); >> } >> } >> >