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X-IronPort-AV: E=McAfee;i="6500,9779,10630"; a="331117118" X-IronPort-AV: E=Sophos;i="5.97,322,1669104000"; d="scan'208";a="331117118" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Feb 2023 19:02:51 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10630"; a="918274147" X-IronPort-AV: E=Sophos;i="5.97,322,1669104000"; d="scan'208";a="918274147" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Feb 2023 19:02:45 -0800 From: "Huang, Ying" To: Linus Torvalds Cc: Andrew Morton , Jan Kara , Vishal Moola , Paulo Alcantara , Matthew Wilcox , David Howells , Steve French , Baolin Wang , Xin Hao , linux-mm@kvack.org, mm-commits@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [GIT PULL] MM updates for 6.3-rc1 References: <20230220135225.91b0f28344c01d5306c31230@linux-foundation.org> Date: Fri, 24 Feb 2023 11:01:49 +0800 In-Reply-To: (Linus Torvalds's message of "Thu, 23 Feb 2023 17:33:37 -0800") Message-ID: <87cz5zdaw2.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 6F05780005 X-Stat-Signature: yqr46a44k8g7d1z94n5z89xpkj1cuwsn X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1677207773-306206 X-HE-Meta: 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 54bvXgQd MFe9fiDSNw4ykXRi15hXICETaGFGS/x14qovvYo5qKRIJf1dW3McXHjVm9a2+wdRNtKMfZafTKnxo+whesctXq/lI37DVfODtve1Vg05XbxrIaXmqFf53GNpT5BUyoj9SpyuKsGfgJ+aeWjKYUsjtSBBDaNxlb+RaZGMaYwrlLHhPF/8870A8lReOB14ELv8ROuL8y52GF69WXWjQ6XV9y8J/rM0q4/3rTOHZXpWbIJWdAlLzRE5j2WhBKtq88vl6Z1GVScUfYNFn5pt4r9rKg4HoLVBKCWIKKZdh 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: Linus Torvalds writes: > > - gcc 12.2.1 quite reasonable complains about some of the new MM code: > > mm/migrate.c: In function =E2=80=98__migrate_folio_extract=E2=80=99: > mm/migrate.c:1050:20: note: randstruct: casting between randomized > structure pointer types (ssa): =E2=80=98struct anon_vma=E2=80=99 and =E2= =80=98struct > address_space=E2=80=99 > > 1050 | *anon_vmap =3D (void *)dst->mapping; > | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~ > > and while this doesn't cause a build failure ("note" is different > from "warning"), I do think something needs to be done. Gcc is right. > This code seems to *work* simply because it's intentionally > mis-casting pointers, Yes. The mis-casting is intentional. I just need some place to hold the data temporarily (save in __migrate_folio_record() and clear in __migrate_folio_extract()). And "dst" is newly allocated folio. > but I think it needs to be seriously looked at and something done to > make gcc happy (and a *LARGE* comment about it). Sure. I will check whether there's some way to make gcc happy and add some comments about that. There's some comments for __migrate_folio_extract(), but that's isn't enough apprently.) > That last note is not some merge result, it's purely about the new MM cod= e. > [snip] Best Regards, Huang, Ying