The patch titled mm: flush dcache before writing into page to avoid alias has been removed from the -mm tree. Its filename was mm-flush-dcache-before-writing-into-page-to-avoid-alias.patch This patch was dropped because it was merged into mainline or a subsystem tree The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: mm: flush dcache before writing into page to avoid alias From: anfei zhou <anfei.zhou@xxxxxxxxx> The cache alias problem will happen if the changes of user shared mapping is not flushed before copying, then user and kernel mapping may be mapped into two different cache line, it is impossible to guarantee the coherence after iov_iter_copy_from_user_atomic. So the right steps should be: flush_dcache_page(page); kmap_atomic(page); write to page; kunmap_atomic(page); flush_dcache_page(page); More precisely, we might create two new APIs flush_dcache_user_page and flush_dcache_kern_page to replace the two flush_dcache_page accordingly. Here is a snippet tested on omap2430 with VIPT cache, and I think it is not ARM-specific: int val = 0x11111111; fd = open("abc", O_RDWR); addr = mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); *(addr+0) = 0x44444444; tmp = *(addr+0); *(addr+1) = 0x77777777; write(fd, &val, sizeof(int)); close(fd); The results are not always 0x11111111 0x77777777 at the beginning as expected. Sometimes we see 0x44444444 0x77777777. Signed-off-by: Anfei <anfei.zhou@xxxxxxxxx> Cc: Russell King <rmk@xxxxxxxxxxxxxxxx> Cc: Miklos Szeredi <miklos@xxxxxxxxxx> Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: <linux-arch@xxxxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/fuse/file.c | 3 +++ mm/filemap.c | 3 +++ 2 files changed, 6 insertions(+) diff -puN fs/fuse/file.c~mm-flush-dcache-before-writing-into-page-to-avoid-alias fs/fuse/file.c --- a/fs/fuse/file.c~mm-flush-dcache-before-writing-into-page-to-avoid-alias +++ a/fs/fuse/file.c @@ -828,6 +828,9 @@ static ssize_t fuse_fill_write_pages(str if (!page) break; + if (mapping_writably_mapped(mapping)) + flush_dcache_page(page); + pagefault_disable(); tmp = iov_iter_copy_from_user_atomic(page, ii, offset, bytes); pagefault_enable(); diff -puN mm/filemap.c~mm-flush-dcache-before-writing-into-page-to-avoid-alias mm/filemap.c --- a/mm/filemap.c~mm-flush-dcache-before-writing-into-page-to-avoid-alias +++ a/mm/filemap.c @@ -2232,6 +2232,9 @@ again: if (unlikely(status)) break; + if (mapping_writably_mapped(mapping)) + flush_dcache_page(page); + pagefault_disable(); copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes); pagefault_enable(); _ Patches currently in -mm which might be from anfei.zhou@xxxxxxxxx are origin.patch -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html