On 09/08/2010 09:47 PM, Andrew Morton wrote: > On Tue, 7 Sep 2010 13:45:34 -0700 > Gary King <gking@xxxxxxxxxx> wrote: > >> I have been seeing problems on Tegra 2 (ARMv7 SMP) systems with HIGHMEM >> enabled on 2.6.35 (plus some patches targetted at 2.6.36 to perform >> cache maintenance lazily), and the root cause appears to be that the >> mm bouncing code is calling flush_dcache_page before it copies the >> bounce buffer into the bio. >> >> The patch below reorders these two operations, and eliminates numerous >> arbitrary application crashes on my dev system. >> >> Gary >> >> -- >> >From 678c9bca8d8a8f254f28af91e69fad3aa1be7593 Mon Sep 17 00:00:00 2001 >> From: Gary King <gking@xxxxxxxxxx> >> Date: Mon, 6 Sep 2010 15:37:12 -0700 >> Subject: bounce: call flush_dcache_page after bounce_copy_vec >> >> the bounced page needs to be flushed after data is copied into it, >> to ensure that architecture implementations can synchronize >> instruction and data caches if necessary. >> >> Signed-off-by: Gary King <gking@xxxxxxxxxx> >> --- >> mm/bounce.c | 2 +- >> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/mm/bounce.c b/mm/bounce.c >> index 13b6dad..1481de6 100644 >> --- a/mm/bounce.c >> +++ b/mm/bounce.c >> @@ -116,8 +116,8 @@ static void copy_to_high_bio_irq(struct bio *to, struct bio *from) >> */ >> vfrom = page_address(fromvec->bv_page) + tovec->bv_offset; >> >> - flush_dcache_page(tovec->bv_page); >> bounce_copy_vec(tovec, vfrom); >> + flush_dcache_page(tovec->bv_page); >> } >> } > > Oh my, that was bad. Indeed, I wonder how that could have been wrong for so long. > I queued your fix for 2.6.36 and tagged it for -stable backporting, > thanks. Thanks, you can add my acked-by. -- Jens Axboe -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>