From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@arm.linux.org.uk (Russell King - ARM Linux) Date: Mon, 4 Apr 2011 14:37:18 +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: <20110404133718.GC22480@n2100.arm.linux.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Apr 04, 2011 at 02:27:45PM +0100, Catalin Marinas wrote: > 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? No, I do not agree.