linux-kernel - Re: [PATCH] fs/pipe: use kvcalloc to allocate a pipe

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Date:   Wed, 5 Jan 2022 22:50:06 +0000
From:   Dmitry Safonov <0x7f454c46@...il.com>
To:     Andrei Vagin <avagin@...il.com>
Cc:     linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH] fs/pipe: use kvcalloc to allocate a pipe_buffer array

On 1/5/22 21:47, Andrei Vagin wrote:
> On Tue, Jan 4, 2022 at 10:54 PM Dmitry Safonov <0x7f454c46@...il.com> wrote:
[..]
>> Otherwise this loop in free_pipe_info() may become lockup on some ugly
>> platforms with INTMAX allocation reachable, I think. I may be wrong :-)
> 
> This change looks reasonable, it makes types of local variables consistent
> with proper fields of pipe_inode_info. But right now, the maximum pipe size
> is limited by (1<<31) (look at round_pipe_size) and so we don't have a real
> issue here.

Right you are, I haven't noticed it.

Hmm,
:	if (size > (1U << 31))
:		return 0;

Isn't size == (1U << 31) a negative integer on 32-bit?

[probably, the question is not very related to your patch, though]

Thanks,
          Dmitry