From: Jason Gunthorpe <jgg@ziepe.ca>
To: "Mateusz Jończyk" <mat.jonczyk@o2.pl>
Cc: netdev@vger.kernel.org,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
David Laight <David.Laight@ACULAB.COM>,
Andrew Morton <akpm@linux-foundation.org>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
Anshuman Khandual <anshuman.khandual@arm.com>,
linux-rdma@vger.kernel.org
Subject: Re: "mm: uninline copy_overflow()" breaks i386 build in Mellanox MLX4
Date: Mon, 25 Apr 2022 20:13:05 -0300 [thread overview]
Message-ID: <20220425231305.GY64706@ziepe.ca> (raw)
In-Reply-To: <dbd203b1-3988-4c9c-909c-2d1f7f173a0d@o2.pl>
On Thu, Apr 21, 2022 at 10:47:01PM +0200, Mateusz Jończyk wrote:
> Hello,
>
> commit ad7489d5262d ("mm: uninline copy_overflow()")
>
> breaks for me a build for i386 in the Mellanox MLX4 driver:
>
> In file included from ./arch/x86/include/asm/preempt.h:7,
> from ./include/linux/preempt.h:78,
> from ./include/linux/percpu.h:6,
> from ./include/linux/context_tracking_state.h:5,
> from ./include/linux/hardirq.h:5,
> from drivers/net/ethernet/mellanox/mlx4/cq.c:37:
> In function ‘check_copy_size’,
> inlined from ‘copy_to_user’ at ./include/linux/uaccess.h:159:6,
> inlined from ‘mlx4_init_user_cqes’ at drivers/net/ethernet/mellanox/mlx4/cq.c:317:9,
> inlined from ‘mlx4_cq_alloc’ at drivers/net/ethernet/mellanox/mlx4/cq.c:394:10:
> ./include/linux/thread_info.h:228:4: error: call to ‘__bad_copy_from’ declared with attribute error: copy source size is too small
> 228 | __bad_copy_from();
> | ^~~~~~~~~~~~~~~~~
> make[5]: *** [scripts/Makefile.build:288: drivers/net/ethernet/mellanox/mlx4/cq.o] Błąd 1
> make[4]: *** [scripts/Makefile.build:550: drivers/net/ethernet/mellanox/mlx4] Błąd 2
> make[3]: *** [scripts/Makefile.build:550: drivers/net/ethernet/mellanox] Błąd 2
> make[2]: *** [scripts/Makefile.build:550: drivers/net/ethernet] Błąd 2
> make[1]: *** [scripts/Makefile.build:550: drivers/net] Błąd 2
>
> Reverting this commit fixes the build. Disabling Mellanox Ethernet drivers
> in Kconfig (tested only with also disabling of all Infiniband support) also fixes the build.
>
> It appears that uninlining of copy_overflow() causes GCC to analyze the code deeper.
This looks like a compiler bug to me, array_size(entries, cqe_size)
cannot be known at compile time, so the __builtin_constant_p(bytes)
should be compile time false meaning the other two bad branches should
have been eliminated.
Jason
next prev parent reply other threads:[~2022-04-25 23:13 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-21 20:47 "mm: uninline copy_overflow()" breaks i386 build in Mellanox MLX4 Mateusz Jończyk
2022-04-25 23:13 ` Jason Gunthorpe [this message]
2022-06-09 18:51 ` Linux kernel: " Mateusz Jończyk
2022-06-13 8:53 ` Richard Biener
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