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From: Matthew Wilcox <willy@infradead.org>
To: Xiaofeng Yuan <yuanxiaofeng1@huawei.com>
Cc: keescook@chromium.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC] usercopy: optimize stack check flow when the
Date: Tue, 14 Aug 2018 05:34:54 -0700	[thread overview]
Message-ID: <20180814123454.GA25328@bombadil.infradead.org> (raw)
In-Reply-To: <1534249051-56879-1-git-send-email-yuanxiaofeng1@huawei.com>

On Tue, Aug 14, 2018 at 08:17:31PM +0800, Xiaofeng Yuan wrote:
> The check_heap_object() checks the spanning multiple pages and slab.
> When the page-spanning test is disabled, the check_heap_object() is
> redundant for spanning multiple pages. However, the kernel stacks are
> multiple pages under certain conditions: CONFIG_ARCH_THREAD_STACK_ALLOCATOR
> is not defined and (THREAD_SIZE >= PAGE_SIZE). At this point, We can skip
> the check_heap_object() for kernel stacks to improve performance.
> Similarly, the virtually-mapped stack can skip check_heap_object() also,
> beacause virt_addr_valid() will return.

Why not just check_stack_object() first, then check_heap_object() second?

  reply	other threads:[~2018-08-14 12:34 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-14 12:17 [PATCH RFC] usercopy: optimize stack check flow when the Xiaofeng Yuan
2018-08-14 12:34 ` Matthew Wilcox [this message]
2018-08-14 13:02   ` [PATCH RFC] usercopy: optimize stack check flow when the page-spanning test is disabled Yuanxiaofeng (XiAn)
2018-08-14 13:09     ` Matthew Wilcox
2018-08-14 18:54     ` Kees Cook
2018-08-15 11:59       ` Yuanxiaofeng (XiAn)

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