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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 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 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 7D4EF18000A X-Stat-Signature: o8zuot8edp6oqjzxadtq9exegqy3pmbx X-Rspam-User: X-HE-Tag: 1784625799-276458 X-HE-Meta: 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 DeO/5NWW yVs0NE38crygynT4lzI3fXYJyecXAv4XgkfEAHo+Ognq0v6ogpB/Lc+Ijlk5Gj+YCS5T5KXjiF4CGUWK+umarnkuYmgkKybOtObMvqLrEfaqOS+1Qv75doyLEJosqFnSh2v1OE9hWwYDnanWvIn5k8DN9u/1rbl2VJplM4xZMEco2uu/2zVz2G0odedH/a+birFK3ahdf4FHu1rGPKZiFRIEzUhb5BgIqPi1/dpS6nYKEi3iaerSXjJHmKGVMqxSp8eQ8XsJmFSd7zp/ZrWoD1pMRH1W/x3GxVlWKQSqTxUib6i+b9rknNorvdJGIsGQCFsxV7t7me4BarstHOJWw1w1L73QoAgaVQgh7C//rP/NFBr0B5ZCVCsDg50A3QqwAKQxdLwGqW+urmyw= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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); >> } >> } >> >