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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2015-09-22 14:59:12 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-09-22 15:09:53 -0700
commit8a04446ab0cf4f35d9f583cd6adcbf7c534e4995 (patch)
treec0a245eb875c5399b8c02b6ddcb9d10e303d9e0b /mm
parent09f7298100ea9767324298ab0c7979f6d7463183 (diff)
mm, dax: VMA with vm_ops->pfn_mkwrite wants to be write-notified
For VM_PFNMAP and VM_MIXEDMAP we use vm_ops->pfn_mkwrite instead of vm_ops->page_mkwrite to notify abort write access. This means we want vma->vm_page_prot to be write-protected if the VMA provides this vm_ops. A theoretical scenario that will cause these missed events is: On writable mapping with vm_ops->pfn_mkwrite, but without vm_ops->page_mkwrite: read fault followed by write access to the pfn. Writable pte will be set up on read fault and write fault will not be generated. I found it examining Dave's complaint on generic/080: http://lkml.kernel.org/g/20150831233803.GO3902@dastard Although I don't think it's the reason. It shouldn't be a problem for ext2/ext4 as they provide both pfn_mkwrite and page_mkwrite. [akpm@linux-foundation.org: add local vm_ops to avoid 80-cols mess] Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Yigal Korman <yigal@plexistor.com> Acked-by: Boaz Harrosh <boaz@plexistor.com> Cc: Matthew Wilcox <matthew.r.wilcox@intel.com> Cc: Jan Kara <jack@suse.cz> Cc: Dave Chinner <david@fromorbit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/mmap.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index c739d6db7193..79bcc9f92e48 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1490,13 +1490,14 @@ SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
int vma_wants_writenotify(struct vm_area_struct *vma)
{
vm_flags_t vm_flags = vma->vm_flags;
+ const struct vm_operations_struct *vm_ops = vma->vm_ops;
/* If it was private or non-writable, the write bit is already clear */
if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED)))
return 0;
/* The backer wishes to know when pages are first written to? */
- if (vma->vm_ops && vma->vm_ops->page_mkwrite)
+ if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite))
return 1;
/* The open routine did something to the protections that pgprot_modify