aka: do_anonymous_page-race.patch
From: Andrea Arcangeli <[EMAIL PROTECTED]>
Subject: Race condition in userspace testcase
References: 46948, LTC11574
NOT IN MAINLINE
Additional Comment #103 From Andrea Arcangeli 2004-10-15 19:41
the last patch I attached is the safest I believe.
I'm not sure if a lock_unlock or lock_unlock is always guaranteed to happen
after the I/O, and this makes sure no race can happen anymore.
---
fs/bio.c | 9 +++++++++
1 file changed, 9 insertions(+)
--- a/fs/bio.c 2007-07-08 19:32:17.000000000 -0400
+++ b/fs/bio.c 2007-08-27 14:01:21.000000000 -0400
@@ -1028,6 +1028,15 @@ void bio_endio(struct bio *bio, unsigned
bio->bi_size -= bytes_done;
bio->bi_sector += (bytes_done >> 9);
+ if (bio_data_dir(bio) == READ)
+ /*
+ * If the current cpu has written to the page by hand
+ * without dma, we must enforce ordering to be sure
+ * this written data will be visible before we expose
+ * the page contents to other cpus (for example with
+ * a set_pte).
+ */
+ smp_wmb();
if (bio->bi_end_io)
bio->bi_end_io(bio, bytes_done, error);
}
--
Thanks,
Oliver
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
