From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 18 Oct 2006 23:33:02 -0700 From: Andrew Morton Subject: Re: [PATCH] mm:D-cache aliasing issue in cow_user_page Message-Id: <20061018233302.a067d1e7.akpm@osdl.org> In-Reply-To: <8764ejqp52.fsf@sw.ru> References: <8764ejqp52.fsf@sw.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Dmitriy Monakhov Cc: Linux Kernel , Linux Memory Management List-ID: On Tue, 17 Oct 2006 13:15:37 +0400 Dmitriy Monakhov wrote: > from mm/memory.c: > 1434 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va) > 1435 { > 1436 /* > 1437 * If the source page was a PFN mapping, we don't have > 1438 * a "struct page" for it. We do a best-effort copy by > 1439 * just copying from the original user address. If that > 1440 * fails, we just zero-fill it. Live with it. > 1441 */ > 1442 if (unlikely(!src)) { > 1443 void *kaddr = kmap_atomic(dst, KM_USER0); > 1444 void __user *uaddr = (void __user *)(va & PAGE_MASK); > 1445 > 1446 /* > 1447 * This really shouldn't fail, because the page is there > 1448 * in the page tables. But it might just be unreadable, > 1449 * in which case we just give up and fill the result with > 1450 * zeroes. > 1451 */ > 1452 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) > 1453 memset(kaddr, 0, PAGE_SIZE); > 1454 kunmap_atomic(kaddr, KM_USER0); > #### D-cache have to be flushed here. > #### It seems it is just forgotten. > > 1455 return; > 1456 > 1457 } > 1458 copy_user_highpage(dst, src, va); > #### Ok here. flush_dcache_page() called from this func if arch need it > 1459 } > This page has just been allocated and is private to the caller - there can be no userspace mappings of it. -- 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