From mboxrd@z Thu Jan 1 00:00:00 1970 From: catalin.marinas@arm.com (Catalin Marinas) Date: Mon, 4 Apr 2011 14:27:45 +0100 Subject: [PATCH 4/4] Do not call flush_cache_user_range with mmap_sem held In-Reply-To: References: <1292302659-1863-1-git-send-email-john.stultz@linaro.org> <1292302659-1863-5-git-send-email-john.stultz@linaro.org> <20101214093002.GA18425@n2100.arm.linux.org.uk> <20101214190503.GB24303@n2100.arm.linux.org.uk> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Russell, On 14 December 2010 21:08, Catalin Marinas wrote: > On Tuesday, 14 December 2010, Russell King - ARM Linux > wrote: >> On Tue, Dec 14, 2010 at 05:51:36PM +0000, Catalin Marinas wrote: >>> But what's the problem if such mapping disappears? The >>> flush_cache_user_range code should just skip such pages. >> >> That's only half the story. >> >> What if someone remaps something over that range before the cache >> maintainence has completed. > > That someone remapping the same range can only be a thread of the same > process. If the code was so badly written as to unmap ranges of memory > when a thread actively uses it, then it probably deserves any > corruption. I haven't seen any more replies in this thread but I still think it's a real problem as John reported. Do you agree with the original patch? That's the original post if you no longer have it in your inbox: http://article.gmane.org/gmane.linux.ports.arm.kernel/99356 -- Catalin