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[2003:cb:c712:fa00:38eb:93ad:be38:d469]) by smtp.gmail.com with ESMTPSA id j9-20020a05600c190900b004166b960469sm2858722wmq.38.2024.04.10.10.03.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 10 Apr 2024 10:03:22 -0700 (PDT) Message-ID: <79051196-601a-406c-9572-033173848bfb@redhat.com> Date: Wed, 10 Apr 2024 19:03:21 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/shmem: Inline shmem_is_huge() for disabled transparent hugepages To: Peter Xu Cc: Sumanth Korikkar , akpm@linux-foundation.org, linux-mm@kvack.org, hughd@google.com, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, iii@linux.ibm.com, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Jason Gunthorpe References: <20240409155407.2322714-1-sumanthk@linux.ibm.com> <594dbec7-b560-44e5-a684-93dcb8ba85df@redhat.com> <29b613a8-f0d5-4f5f-adbc-d64ed8908044@redhat.com> <1ce2fe6c-b56a-4582-a5d8-babc8fccef52@redhat.com> <61a3bd6b-a352-4e02-8357-81ac7b9f2848@redhat.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 1F24E40043 X-Stat-Signature: mwqdszffdcy4udwk31ufqwdg85x39a4e X-HE-Tag: 1712768607-257577 X-HE-Meta: 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 yQ5ackp2 gIIptGL6WExcWZ5tiMeQwXtPFAntgo6rLHOcdmfMXx9aJ5JpdOD3zKRoaXHa62oKfntuvkGsJs65sB2Cymu1jqAmrhy5JtqTkw5lo/tYu9i/dVnby/5Qc52o3I11A9Zw6FMSuYMmxoHiMhyUY8Rix4+Hi1IKQmHHdqScm2/tRMddkxZ+tsVX/ksGrZGtcead+mV5SN+nVghPD7xWkgoLLaRwfpA== 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 10.04.24 18:51, Peter Xu wrote: > On Wed, Apr 10, 2024 at 06:40:55PM +0200, David Hildenbrand wrote: >> On 10.04.24 18:33, Peter Xu wrote: >>> On Wed, Apr 10, 2024 at 06:12:34PM +0200, David Hildenbrand wrote: >>>> On 10.04.24 18:07, Sumanth Korikkar wrote: >>>>> On Wed, Apr 10, 2024 at 05:51:28PM +0200, David Hildenbrand wrote: >>>>>> On 10.04.24 17:26, Sumanth Korikkar wrote: >>>>>>> On Wed, Apr 10, 2024 at 02:34:35PM +0200, David Hildenbrand wrote: >>>>>>>> On 09.04.24 17:54, Sumanth Korikkar wrote: >>>>>>>>> In order to minimize code size (CONFIG_CC_OPTIMIZE_FOR_SIZE=y), >>>>>>>>> compiler might choose to make a regular function call (out-of-line) for >>>>>>>>> shmem_is_huge() instead of inlining it. When transparent hugepages are >>>>>>>>> disabled (CONFIG_TRANSPARENT_HUGEPAGE=n), it can cause compilation >>>>>>>>> error. >>>>>>>>> >>>>>>>>> mm/shmem.c: In function ‘shmem_getattr’: >>>>>>>>> ./include/linux/huge_mm.h:383:27: note: in expansion of macro ‘BUILD_BUG’ >>>>>>>>> 383 | #define HPAGE_PMD_SIZE ({ BUILD_BUG(); 0; }) >>>>>>>>> | ^~~~~~~~~ >>>>>>>>> mm/shmem.c:1148:33: note: in expansion of macro ‘HPAGE_PMD_SIZE’ >>>>>>>>> 1148 | stat->blksize = HPAGE_PMD_SIZE; >>>>>>>>> >>>>>>>>> To prevent the possible error, always inline shmem_is_huge() when >>>>>>>>> transparent hugepages are disabled. >>>>>>>>> >>>>>>>> >>>>>>>> Do you know which commit introduced that? >>>>>>> Hi David, >>>>>>> >>>>>>> Currently with CONFIG_CC_OPTIMIZE_FOR_SIZE=y and expirementing with >>>>>>> -fPIC kernel compiler option, I could see this error on s390. >>>>>> >>>>>> Got it. I assume on Linus' tree, not mm/unstable? >>>>> >>>>> It's not yet upstream. >>>>>> >>>>>>> >>>>>>> However, default kernel compiler options doesnt end up with the above >>>>>>> pattern right now. >>>>>> >>>>>> Okay, just asking if this is related to recent HPAGE_PMD_SIZE changes: >>>>>> >>>>>> commit c1a1e497a3d5711dbf8fa6d7432d6b83ec18c26f >>>>>> Author: Peter Xu >>>>>> Date: Wed Mar 27 11:23:22 2024 -0400 >>>>>> >>>>>> mm: make HPAGE_PXD_* macros even if !THP >>>>>> >>>>>> Which is still in mm-unstable and not upstream. >>>>> >>>>> Not related to this commit. I tried on master branch. >>>> >>>> Thanks! Can you try with Peters patch? (ccing Peter) >>>> >>>> If I am not wrong, that should also resolve the issue you are seeing. >>> >>> David, >>> >>> Do you mean this one? >>> >>> https://lore.kernel.org/all/20240403013249.1418299-4-peterx@redhat.com/ >>> >> >> No, I meant: >> >> https://lore.kernel.org/all/20240327152332.950956-4-peterx@redhat.com/ >> >> which removes the "#define HPAGE_PMD_SIZE ({ BUILD_BUG(); 0; })" that we >> seem to trigger here. >> >> >> ... but it's been a long day, so maybe I'm all wrong :) > > Ah.. So I thought it was one step further. :) > > Then that shouldn't be the case; it didn't remove it but defined properly > with HPAGE_PMD_SHIFT: > > +#define HPAGE_PMD_SIZE ((1UL) << HPAGE_PMD_SHIFT) > > Now we even have that properly defined for HUGETLB_PAGE, while prior to > that we should hit this issue easier (even with !THP+HUGETLB_PAGE). Ah, now I spot #define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; }) :) sorry for the noise! To the original patch here Acked-by: David Hildenbrand -- Cheers, David / dhildenb