> On 02/27/2016 03:28 PM, John Paul Adrian Glaubitz wrote: > > Hi Hans! > > > > On 02/27/2016 03:20 PM, Geert Uytterhoeven wrote: > >>> I noticed that 4.1 was ok and v4.2 wasn't, so I did a git bisect and ended up with > >>> commit 8222dbe21e79338de92d5e1956cd1e3994cc9f93 (sched/preempt, mm/fault: Decouple > >>> preemption from the page fault logic) as the culprit. > > > > If you like, please report this the kernel bug tracker and set > > "Hardware" to "SuperH". This way we are able to keep track of > > the issue. > > > > I think Yoshinori Sato and Rich Felker will have a look at this. > > > > Adrian > > > > Done: https://bugzilla.kernel.org/show_bug.cgi?id=113321 > > Regards, > > Hans > Looks like the code then requires to not be allowed to sleep/preempt in these sections (just like kmap_atomic, or kmap_coherent on mips). So the fix should be simple as (untested): >From d29f0d0cb670175c688cdd181c7a693d28b27a33 Mon Sep 17 00:00:00 2001 From: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx> Date: Mon, 29 Feb 2016 09:19:24 +0100 Subject: [PATCH] sched/preempt, sh: kmap_coherent relies on disabled preemption kmap_coherent needs disabled preemption to not schedule in the critical section, just like kmap_coherent on mips and kmap_atomic in general. Fixes: 8222dbe21e79 "sched/preempt, mm/fault: Decouple preemption from the page fault logic" Reported-by: Hans Verkuil <hverkuil@xxxxxxxxx> Signed-off-by: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx> --- arch/sh/mm/kmap.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/sh/mm/kmap.c b/arch/sh/mm/kmap.c index ec29e14..bf25d7c 100644 --- a/arch/sh/mm/kmap.c +++ b/arch/sh/mm/kmap.c @@ -36,6 +36,7 @@ void *kmap_coherent(struct page *page, unsigned long addr) BUG_ON(!test_bit(PG_dcache_clean, &page->flags)); + preempt_disable(); pagefault_disable(); idx = FIX_CMAP_END - @@ -64,4 +65,5 @@ void kunmap_coherent(void *kvaddr) } pagefault_enable(); + preempt_enable(); } -- 2.3.9 David
