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Wed, 20 Nov 2024 07:00:27 -0800 (PST) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-7f8c1dcf424sm9688998a12.78.2024.11.20.07.00.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Nov 2024 07:00:27 -0800 (PST) Date: Wed, 20 Nov 2024 07:00:26 -0800 From: Guenter Roeck To: Geert Uytterhoeven Cc: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Jens Axboe , Pavel Begunkov , Mike@rox.of.borg, Rapoport@rox.of.borg, Christian Brauner , Kees Cook , Jann Horn , linux-mm@kvack.org, io-uring@vger.kernel.org, linux-m68k@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] slab: Fix too strict alignment check in create_cache() Message-ID: <5df87ac7-9779-4a9e-b3ca-6aeddb1a4896@roeck-us.net> References: <80c767a5d5927c099aea5178fbf2c897b459fa90.1732106544.git.geert@linux-m68k.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <80c767a5d5927c099aea5178fbf2c897b459fa90.1732106544.git.geert@linux-m68k.org> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 384EF1A0019 X-Stat-Signature: tcewn8bumj6jimjidoagjmpdikqceqqm X-Rspam-User: X-HE-Tag: 1732114766-585960 X-HE-Meta: U2FsdGVkX185GMdxlFkgI945yVCnE6c+yldMFdiO6WxutoWE/Qo96ScyppJEcwg6u6yRsjbfuW+lufq5LOP3cvJr2AIr/PSAUBd9A4mU0rPN0q5ZiYxQIzyHve++rtfqf/U1D1kS+INys4+31P281ZwX7C+oRhi40H7WfA5ivaHgIw0WQplDpBIMwNN5EwDyqsBgIzKPFAADodamKwZaausi63sUo/Wm54QiR7vqhfZMMaAE8r9P6rEQ2cZUdqtH9lQKQFPws+RDKDpAVpdF4QNA4zpl6pDxgBBMnyRsdIHwViy+w4506yinvdTXaPmeZT8ddfZj+6keIOqN57nyQi4YvDg78JnTyhsABakrXHNjpMk7TV1l03rrjGuWI0e9+Be+Qi51xbGKjLVdlg/50Q0eMI9uzXcNWVkAuIqfWszrYiEbMSXBn5pzH/4wahiZLs/HwgRL6D+0BNosiGrMX+YwzrYuIZfpXqnC7ByNg8TlVTaiLZoe9kfeLqVSEeaS4GZJMvMF8RIe9BRVKYzUuAdlM754ClaKdrpqtfpXzefepAOxYf3Fw9dcwy074gvCXU+lsXZh8z2+YuqrwlO39H5Aber/s4uCS9Q9pqyVsosqzIHCW99rPbrbIHISLhFi27acCoYA54ru+yXPB3DvHbS+Q3YfA0bam9cdia0udfUF4CJO4uaxW9FuM9yUDWTh62/nit0sEK3xi8vaNLHwJa4JVO1zCpGMcv2Qq/W0euINxV7d+O0hm85/kQPSz17IcibSYHedscoMsqAvjE3OyJBRTW0fUBo7ivSvtq62uBWLV6L6p3mljPJP2thHdrPkDqQ1CyJc1S+POv5pHOePwwx8MdEUrXYd0Q9G7piBU3huu4Sq7BZzfuvBCWE1W1s783aZ01TtpMZOl13T+tgmqaSTScQJVvhYCMKXj1xiyuAaJCWPDWPtqAm42kjThb4TeAZvKuLOrvQ2hx+J5Ur UtW4JcWY 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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: List-Subscribe: List-Unsubscribe: On Wed, Nov 20, 2024 at 01:46:21PM +0100, Geert Uytterhoeven wrote: > On m68k, where the minimum alignment of unsigned long is 2 bytes: > > Kernel panic - not syncing: __kmem_cache_create_args: Failed to create slab 'io_kiocb'. Error -22 > CPU: 0 UID: 0 PID: 1 Comm: swapper Not tainted 6.12.0-atari-03776-g7eaa1f99261a #1783 > Stack from 0102fe5c: > 0102fe5c 00514a2b 00514a2b ffffff00 00000001 0051f5ed 00425e78 00514a2b > 0041eb74 ffffffea 00000310 0051f5ed ffffffea ffffffea 00601f60 00000044 > 0102ff20 000e7a68 0051ab8e 004383b8 0051f5ed ffffffea 000000b8 00000007 > 01020c00 00000000 000e77f0 0041e5f0 005f67c0 0051f5ed 000000b6 0102fef4 > 00000310 0102fef4 00000000 00000016 005f676c 0060a34c 00000010 00000004 > 00000038 0000009a 01000000 000000b8 005f668e 0102e000 00001372 0102ff88 > Call Trace: [<00425e78>] dump_stack+0xc/0x10 > [<0041eb74>] panic+0xd8/0x26c > [<000e7a68>] __kmem_cache_create_args+0x278/0x2e8 > [<000e77f0>] __kmem_cache_create_args+0x0/0x2e8 > [<0041e5f0>] memset+0x0/0x8c > [<005f67c0>] io_uring_init+0x54/0xd2 > > The minimal alignment of an integral type may differ from its size, > hence is not safe to assume that an arbitrary freeptr_t (which is > basically an unsigned long) is always aligned to 4 or 8 bytes. > > As nothing seems to require the additional alignment, it is safe to fix > this by relaxing the check to the actual minimum alignment of freeptr_t. > > Fixes: aaa736b186239b7d ("io_uring: specify freeptr usage for SLAB_TYPESAFE_BY_RCU io_kiocb cache") > Fixes: d345bd2e9834e2da ("mm: add kmem_cache_create_rcu()") > Reported-by: Guenter Roeck > Closes: https://lore.kernel.org/37c588d4-2c32-4aad-a19e-642961f200d7@roeck-us.net > Signed-off-by: Geert Uytterhoeven On m68k: Tested-by: Guenter Roeck