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bh=YpOQ8oryHFElt6K2lv1s9uR3pjCugGSDXwduZIz+uYs=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=V70rQ0s2Qm2ej6zbgltA2RufuWvBRV9Ayj4zAZYVcHrdb/Bn+PW3LafZ0GC4isuxZ E/YE8SeNl9MOKCQg82KJJtI751TWD3J4enIggJZqGgUcPyQTkY6Y7uXzr+y1lWQTAq +0LGnO92BttDVnyIL9kS9MSztAzklqk3l/wwZa5E= Date: Sat, 4 Mar 2023 15:20:58 -0800 From: Andrew Morton To: Linus Torvalds Cc: "Huang, Ying" , linux-mm@kvack.org, mm-commits@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [GIT PULL] hotfixes for 6.3-rc1 Message-Id: <20230304152058.de91bf7abf424383ce31d500@linux-foundation.org> In-Reply-To: References: <20230304131528.4645d19a2ab897fb7518159e@linux-foundation.org> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: AA56AA0003 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: 9um4bfmmuzimo3n3qkpsoqkbjytkp5mc X-HE-Tag: 1677972061-500989 X-HE-Meta: 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 WK2uGPho 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 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: On Sat, 4 Mar 2023 14:35:00 -0800 Linus Torvalds wrote: > On Sat, Mar 4, 2023 at 1:15 PM Andrew Morton wrote: > > > > 17 hotfixes. Eight are for MM and seven are for other parts of the > > kernel. Seven are cc:stable and eight address post-6.3 issues or were > > judged unsuitable for -stable backporting. > > Hmm. Since this pull didn't fix the gcc note about playing pointer > games that I get for my allmodconfig test build, and since I _really_ > don't want to have an rc1 release tomorrow with that (valid) warning, > I fixed it up myself. Ah. Ying did it this way: From: Huang Ying Subject: migrate_pages: silence gcc notes for mis-casting Date: Thu, 2 Mar 2023 09:26:10 +0800 The following GCC notes was reported for commit 64c8902ed441 ("migrate_pages: split unmap_and_move() to _unmap() and _move()"). mm/migrate.c: In function `__migrate_folio_extract': mm/migrate.c:1050:20: note: randstruct: casting between randomized structure pointer types (ssa): `struct anon_vma' and `struct address_space' 1050 | *anon_vmap = (void *)dst->mapping; | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~ The casting itself is safe. Because we only use dst->mapping to store the pointer itself temporarily and dst is a newly allocated folio and not used by anyone else during that. But the notes should be silenced and some comments are deserved. So, we do that in this patch. Link: https://lkml.kernel.org/r/20230302012610.17055-1-ying.huang@intel.com Fixes: 64c8902ed441 ("migrate_pages: split unmap_and_move() to _unmap() and _move()") Signed-off-by: "Huang, Ying" Cc: Linus Torvalds Cc: Baolin Wang Cc: Xin Hao Cc: Zi Yan Cc: Yang Shi Cc: Oscar Salvador Cc: Matthew Wilcox Cc: Bharata B Rao Cc: Alistair Popple Signed-off-by: Andrew Morton --- --- a/mm/migrate.c~migrate_pages-silence-gcc-notes-for-mis-casting +++ a/mm/migrate.c @@ -1047,7 +1047,16 @@ static void __migrate_folio_extract(stru int *page_was_mappedp, struct anon_vma **anon_vmap) { - *anon_vmap = (void *)dst->mapping; + struct anon_vma *anon_vma; + + /* + * 2 steps assignment to silence gcc notes for mis-casting. The + * casting is safe. Because we only use dst->mapping to store + * the pointer itself temporarily and dst is a newly allocated + * folio and not used by anyone else during that. + */ + anon_vma = (void *)dst->mapping; + *anon_vmap = anon_vma; *page_was_mappedp = (unsigned long)dst->private; dst->mapping = NULL; dst->private = NULL; _