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Message-Id: <1274825820-10246-2-git-send-email-albert_herranz@yahoo.es>
Date: Wed, 26 May 2010 00:17:00 +0200
From: Albert Herranz <albert_herranz@...oo.es>
To: npiggin@...e.de, jayakumar.lkml@...il.com,
akpm@...ux-foundation.org, torvalds@...ux-foundation.org,
linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-fbdev@...r.kernel.org
Cc: Albert Herranz <albert_herranz@...oo.es>
Subject: [RFT PATCH 2/2] fb_defio: redo fix for non-dirty ptes
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.
LKML-Reference: <20100525160149.GE20853@...top>
Signed-off-by: Albert Herranz <albert_herranz@...oo.es>
---
drivers/video/fb_defio.c | 12 +++++++++++-
1 files changed, 11 insertions(+), 1 deletions(-)
diff --git a/drivers/video/fb_defio.c b/drivers/video/fb_defio.c
index 0e4dcdb..a3e8cc7 100644
--- a/drivers/video/fb_defio.c
+++ b/drivers/video/fb_defio.c
@@ -100,6 +100,16 @@ static int fb_deferred_io_mkwrite(struct vm_area_struct *vma,
/* 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 = {
--
1.7.0.4
--
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