From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 18 Jan 2008 13:27:07 -0800 (PST) From: Linus Torvalds Subject: Re: [PATCH -v6 2/2] Updating ctime and mtime for memory-mapped files In-Reply-To: <4df4ef0c0801181303o6656832g8b63d2a119a86a9c@mail.gmail.com> Message-ID: References: <12006091182260-git-send-email-salikhmetov@gmail.com> <4df4ef0c0801181158s3f783beaqead3d7049d4d3fa7@mail.gmail.com> <4df4ef0c0801181303o6656832g8b63d2a119a86a9c@mail.gmail.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Anton Salikhmetov Cc: Miklos Szeredi , peterz@infradead.org, linux-mm@kvack.org, jakob@unthought.net, linux-kernel@vger.kernel.org, valdis.kletnieks@vt.edu, riel@redhat.com, ksm@42.dk, staubach@redhat.com, jesper.juhl@gmail.com, akpm@linux-foundation.org, protasnb@gmail.com, r.e.wolff@bitwizard.nl, hidave.darkstar@gmail.com, hch@infradead.org List-ID: On Sat, 19 Jan 2008, Anton Salikhmetov wrote: > > Before using pte_wrprotect() the vma_wrprotect() routine uses the > pte_offset_map_lock() macro to get the PTE and to acquire the ptl > spinlock. Why did you say that this code was not SMP-safe? It should > be atomic, I think. It's atomic WITH RESPECT TO OTHER PEOPLE WHO GET THE LOCK. Guess how much another x86 CPU cares when it sets the accessed bit in hardware? > The POSIX standard requires the ctime and mtime stamps to be updated > not later than at the second call to msync() with the MS_ASYNC flag. .. and that is no excuse for bad code. Linus -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org