linux-kernel - Re: [PATCH 1/2] io_uring: Fix io_uring mmap() by using architecture-provided get_unmapped

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Message-ID: <047346f8-9ac4-4990-2885-8bfac47b83a3@kernel.org>
Date:   Mon, 24 Jul 2023 09:39:07 +0200
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Helge Deller <deller@....de>, linux-kernel@...r.kernel.org,
        io-uring@...r.kernel.org, Jens Axboe <axboe@...nel.dk>,
        linux-ia64@...r.kernel.org, linux-parisc@...r.kernel.org
Cc:     matoro <matoro_mailinglist_kernel@...oro.tk>
Subject: Re: [PATCH 1/2] io_uring: Fix io_uring mmap() by using
 architecture-provided get_unmapped_area()

On 21. 07. 23, 17:24, Helge Deller wrote:
> The io_uring testcase is broken on IA-64 since commit d808459b2e31
> ("io_uring: Adjust mapping wrt architecture aliasing requirements").
> 
> The reason is, that this commit introduced an own architecture
> independend get_unmapped_area() search algorithm which finds on IA-64 a
> memory region which is outside of the regular memory region used for
> shared userspace mappings and which can't be used on that platform
> due to aliasing.
> 
> To avoid similar problems on IA-64 and other platforms in the future,
> it's better to switch back to the architecture-provided
> get_unmapped_area() function and adjust the needed input parameters
> before the call. Beside fixing the issue, the function now becomes
> easier to understand and maintain.
> 
> This patch has been successfully tested with the io_uring testcase on
> physical x86-64, ppc64le, IA-64 and PA-RISC machines. On PA-RISC the LTP
> mmmap testcases did not report any regressions.
> 
> Signed-off-by: Helge Deller <deller@....de>
> Cc: Jens Axboe <axboe@...nel.dk>
> Reported-by: matoro <matoro_mailinglist_kernel@...oro.tk>
> Fixes: d808459b2e31 ("io_uring: Adjust mapping wrt architecture aliasing requirements")

Tested-by: Jiri Slaby <jirislaby@...nel.org>

thanks,
-- 
js
suse labs