linux/arch/sh/include
Linus Torvalds 2b047252d0 Fix TLB gather virtual address range invalidation corner cases
Ben Tebulin reported:

 "Since v3.7.2 on two independent machines a very specific Git
  repository fails in 9/10 cases on git-fsck due to an SHA1/memory
  failures.  This only occurs on a very specific repository and can be
  reproduced stably on two independent laptops.  Git mailing list ran
  out of ideas and for me this looks like some very exotic kernel issue"

and bisected the failure to the backport of commit 53a59fc67f ("mm:
limit mmu_gather batching to fix soft lockups on !CONFIG_PREEMPT").

That commit itself is not actually buggy, but what it does is to make it
much more likely to hit the partial TLB invalidation case, since it
introduces a new case in tlb_next_batch() that previously only ever
happened when running out of memory.

The real bug is that the TLB gather virtual memory range setup is subtly
buggered.  It was introduced in commit 597e1c3580 ("mm/mmu_gather:
enable tlb flush range in generic mmu_gather"), and the range handling
was already fixed at least once in commit e6c495a96c ("mm: fix the TLB
range flushed when __tlb_remove_page() runs out of slots"), but that fix
was not complete.

The problem with the TLB gather virtual address range is that it isn't
set up by the initial tlb_gather_mmu() initialization (which didn't get
the TLB range information), but it is set up ad-hoc later by the
functions that actually flush the TLB.  And so any such case that forgot
to update the TLB range entries would potentially miss TLB invalidates.

Rather than try to figure out exactly which particular ad-hoc range
setup was missing (I personally suspect it's the hugetlb case in
zap_huge_pmd(), which didn't have the same logic as zap_pte_range()
did), this patch just gets rid of the problem at the source: make the
TLB range information available to tlb_gather_mmu(), and initialize it
when initializing all the other tlb gather fields.

This makes the patch larger, but conceptually much simpler.  And the end
result is much more understandable; even if you want to play games with
partial ranges when invalidating the TLB contents in chunks, now the
range information is always there, and anybody who doesn't want to
bother with it won't introduce subtle bugs.

Ben verified that this fixes his problem.

Reported-bisected-and-tested-by: Ben Tebulin <tebulin@googlemail.com>
Build-testing-by: Stephen Rothwell <sfr@canb.auug.org.au>
Build-testing-by: Richard Weinberger <richard.weinberger@gmail.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-08-16 08:52:46 -07:00
..
asm Fix TLB gather virtual address range invalidation corner cases 2013-08-16 08:52:46 -07:00
cpu-common/cpu sh: Remove unused sh_pfc_register_info() function 2013-01-25 09:24:30 +09:00
cpu-sh2/cpu sh: Tidy up some of the cpu legacy dma header mess. 2012-05-19 18:30:31 +09:00
cpu-sh2a/cpu sh: sh7269: Fix LCD pinmux 2012-08-09 13:16:55 +09:00
cpu-sh3/cpu sh: Tidy up some of the cpu legacy dma header mess. 2012-05-19 18:30:31 +09:00
cpu-sh4/cpu sh: sh7786: Fix port E, G and J GPIOs 2013-01-25 09:24:19 +09:00
cpu-sh4a/cpu sh: dma: More legacy cpu dma chainsawing. 2012-05-19 20:38:50 +09:00
cpu-sh5/cpu sh: Tidy up some of the cpu legacy dma header mess. 2012-05-19 18:30:31 +09:00
mach-common/mach sh: legacy PCI evt2irq migration. 2012-05-18 17:42:29 +09:00
mach-dreamcast/mach sh: Kill off MAX_DMA_ADDRESS leftovers. 2012-05-19 18:50:09 +09:00
mach-ecovec24/mach UAPI: (Scripted) Convert #include "..." to #include <path/...> in kernel system headers 2012-10-02 18:01:25 +01:00
mach-kfr2r09/mach sh: kfr2r09: Use the backlight API for brightness control 2012-11-21 15:50:02 +01:00
mach-landisk/mach sh: landisk evt2irq migration. 2012-05-18 16:51:36 +09:00
mach-migor/mach fbdev: sh_mobile_lcdc: Remove board configuration board_data field 2012-03-12 22:40:49 +01:00
mach-sdk7786/mach sh: mach-sdk7786: Handle baseboard NMI source selection. 2010-12-17 18:58:04 +09:00
mach-se/mach Merge branch 'sh/dynamic-irq-cleanup' into sh-latest 2012-06-13 12:12:41 +09:00
mach-sh03/mach
mach-x3proto/mach sh: mach-x3proto: Support for baseboard GPIOs. 2010-10-04 02:59:29 +09:00
uapi/asm sh: switch to generic old sigaction() 2013-02-03 18:16:16 -05:00