The patch titled
fb_defio: redo fix for non-dirty ptes
has been added to the -mm tree. Its filename is
fb_defio-redo-fix-for-non-dirty-ptes.patch
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Subject: fb_defio: redo fix for non-dirty ptes
From: Albert Herranz <albert_herranz@xxxxxxxx>
As pointed by Nick Piggin, ->page_mkwrite provides a way to keep a page
locked until the associated PTE is marked dirty.
Re-implement the fix by using this mechanism.
Signed-off-by: Albert Herranz <albert_herranz@xxxxxxxx>
Acked-by: Jaya Kumar <jayakumar.lkml@xxxxxxxxx>
Acked-by: Nick Piggin <npiggin@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/video/fb_defio.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff -puN drivers/video/fb_defio.c~fb_defio-redo-fix-for-non-dirty-ptes drivers/video/fb_defio.c
--- a/drivers/video/fb_defio.c~fb_defio-redo-fix-for-non-dirty-ptes
+++ a/drivers/video/fb_defio.c
@@ -100,6 +100,16 @@ static int fb_deferred_io_mkwrite(struct
/* protect against the workqueue changing the page list */
mutex_lock(&fbdefio->lock);
+ /*
+ * We want the page to remain locked from ->page_mkwrite until
+ * the PTE is marked dirty to avoid page_mkclean() being called
+ * before the PTE is updated, which would leave the page ignored
+ * by defio.
+ * Do this by locking the page here and informing the caller
+ * about it with VM_FAULT_LOCKED.
+ */
+ lock_page(page);
+
/* we loop through the pagelist before adding in order
to keep the pagelist sorted */
list_for_each_entry(cur, &fbdefio->pagelist, lru) {
@@ -121,7 +131,7 @@ page_already_added:
/* come back after delay to process the deferred IO */
schedule_delayed_work(&info->deferred_work, fbdefio->delay);
- return 0;
+ return VM_FAULT_LOCKED;
}
static const struct vm_operations_struct fb_deferred_io_vm_ops = {
_
Patches currently in -mm which might be from albert_herranz@xxxxxxxx are
origin.patch
revert-fb_defio-fix-for-non-dirty-ptes.patch
fb_defio-redo-fix-for-non-dirty-ptes.patch
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