linux-toradex.git/arch/openrisc/mm, branch v4.4.55

vm: add VM_FAULT_SIGSEGV handling support

2015-01-29T18:51:32+00:00

The core VM already knows about VM_FAULT_SIGBUS, but cannot return a
"you should SIGSEGV" error, because the SIGSEGV case was generally
handled by the caller - usually the architecture fault handler.

That results in lots of duplication - all the architecture fault
handlers end up doing very similar "look up vma, check permissions, do
retries etc" - but it generally works.  However, there are cases where
the VM actually wants to SIGSEGV, and applications _expect_ SIGSEGV.

In particular, when accessing the stack guard page, libsigsegv expects a
SIGSEGV.  And it usually got one, because the stack growth is handled by
that duplicated architecture fault handler.

However, when the generic VM layer started propagating the error return
from the stack expansion in commit fee7e49d4514 ("mm: propagate error
from stack expansion even for guard page"), that now exposed the
existing VM_FAULT_SIGBUS result to user space.  And user space really
expected SIGSEGV, not SIGBUS.

To fix that case, we need to add a VM_FAULT_SIGSEGV, and teach all those
duplicate architecture fault handlers about it.  They all already have
the code to handle SIGSEGV, so it's about just tying that new return
value to the existing code, but it's all a bit annoying.

This is the mindless minimal patch to do this.  A more extensive patch
would be to try to gather up the mostly shared fault handling logic into
one generic helper routine, and long-term we really should do that
cleanup.

Just from this patch, you can generally see that most architectures just
copied (directly or indirectly) the old x86 way of doing things, but in
the meantime that original x86 model has been improved to hold the VM
semaphore for shorter times etc and to handle VM_FAULT_RETRY and other
"newer" things, so it would be a good idea to bring all those
improvements to the generic case and teach other architectures about
them too.

Reported-and-tested-by: Takashi Iwai 
Tested-by: Jan Engelhardt 
Acked-by: Heiko Carstens  # "s390 still compiles and boots"
Cc: linux-arch@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds

arch: mm: pass userspace fault flag to generic fault handler

2013-09-12T22:38:01+00:00

Unlike global OOM handling, memory cgroup code will invoke the OOM killer
in any OOM situation because it has no way of telling faults occuring in
kernel context - which could be handled more gracefully - from
user-triggered faults.

Pass a flag that identifies faults originating in user space from the
architecture-specific fault handlers to generic code so that memcg OOM
handling can be improved.

Signed-off-by: Johannes Weiner 
Reviewed-by: Michal Hocko 
Cc: David Rientjes 
Cc: KAMEZAWA Hiroyuki 
Cc: azurIt 
Cc: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: invoke oom-killer from remaining unconverted page fault handlers

2013-07-09T17:33:20+00:00

A few remaining architectures directly kill the page faulting task in an
out of memory situation.  This is usually not a good idea since that
task might not even use a significant amount of memory and so may not be
the optimal victim to resolve the situation.

Since 2.6.29's 1c0fe6e ("mm: invoke oom-killer from page fault") there
is a hook that architecture page fault handlers are supposed to call to
invoke the OOM killer and let it pick the right task to kill.  Convert
the remaining architectures over to this hook.

To have the previous behavior of simply taking out the faulting task the
vm.oom_kill_allocating_task sysctl can be set to 1.

Signed-off-by: Johannes Weiner 
Reviewed-by: Michal Hocko 
Cc: KAMEZAWA Hiroyuki 
Acked-by: David Rientjes 
Acked-by: Vineet Gupta    [arch/arc bits]
Cc: James Hogan 
Cc: David Howells 
Cc: Jonas Bonn 
Cc: Chen Liqin 
Cc: Lennox Wu 
Cc: Chris Metcalf 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/openrisc: prepare for removing num_physpages and simplify mem_init()

2013-07-03T23:07:37+00:00

Prepare for removing num_physpages and simplify mem_init().

Signed-off-by: Jiang Liu 
Acked-by: Jonas Bonn 
Cc: David Howells 
Cc: Arnd Bergmann 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: concentrate modification of totalram_pages into the mm core

2013-07-03T23:07:33+00:00

Concentrate code to modify totalram_pages into the mm core, so the arch
memory initialized code doesn't need to take care of it.  With these
changes applied, only following functions from mm core modify global
variable totalram_pages: free_bootmem_late(), free_all_bootmem(),
free_all_bootmem_node(), adjust_managed_page_count().

With this patch applied, it will be much more easier for us to keep
totalram_pages and zone->managed_pages in consistence.

Signed-off-by: Jiang Liu 
Acked-by: David Howells 
Cc: "H. Peter Anvin" 
Cc: "Michael S. Tsirkin" 
Cc: 
Cc: Arnd Bergmann 
Cc: Catalin Marinas 
Cc: Chris Metcalf 
Cc: Geert Uytterhoeven 
Cc: Ingo Molnar 
Cc: Jeremy Fitzhardinge 
Cc: Jianguo Wu 
Cc: Joonsoo Kim 
Cc: Kamezawa Hiroyuki 
Cc: Konrad Rzeszutek Wilk 
Cc: Marek Szyprowski 
Cc: Mel Gorman 
Cc: Michel Lespinasse 
Cc: Minchan Kim 
Cc: Rik van Riel 
Cc: Rusty Russell 
Cc: Tang Chen 
Cc: Tejun Heo 
Cc: Thomas Gleixner 
Cc: Wen Congyang 
Cc: Will Deacon 
Cc: Yasuaki Ishimatsu 
Cc: Yinghai Lu 
Cc: Russell King 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: enhance free_reserved_area() to support poisoning memory with zero

2013-07-03T23:07:32+00:00

Address more review comments from last round of code review.
1) Enhance free_reserved_area() to support poisoning freed memory with
   pattern '0'. This could be used to get rid of poison_init_mem()
   on ARM64.
2) A previous patch has disabled memory poison for initmem on s390
   by mistake, so restore to the original behavior.
3) Remove redundant PAGE_ALIGN() when calling free_reserved_area().

Signed-off-by: Jiang Liu 
Cc: Geert Uytterhoeven 
Cc: "H. Peter Anvin" 
Cc: "Michael S. Tsirkin" 
Cc: 
Cc: Arnd Bergmann 
Cc: Catalin Marinas 
Cc: Chris Metcalf 
Cc: David Howells 
Cc: Ingo Molnar 
Cc: Jeremy Fitzhardinge 
Cc: Jianguo Wu 
Cc: Joonsoo Kim 
Cc: Kamezawa Hiroyuki 
Cc: Konrad Rzeszutek Wilk 
Cc: Marek Szyprowski 
Cc: Mel Gorman 
Cc: Michel Lespinasse 
Cc: Minchan Kim 
Cc: Rik van Riel 
Cc: Rusty Russell 
Cc: Tang Chen 
Cc: Tejun Heo 
Cc: Thomas Gleixner 
Cc: Wen Congyang 
Cc: Will Deacon 
Cc: Yasuaki Ishimatsu 
Cc: Yinghai Lu 
Cc: Russell King 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: change signature of free_reserved_area() to fix building warnings

2013-07-03T23:07:32+00:00

Change signature of free_reserved_area() according to Russell King's
suggestion to fix following build warnings:

  arch/arm/mm/init.c: In function 'mem_init':
  arch/arm/mm/init.c:603:2: warning: passing argument 1 of 'free_reserved_area' makes integer from pointer without a cast [enabled by default]
    free_reserved_area(__va(PHYS_PFN_OFFSET), swapper_pg_dir, 0, NULL);
    ^
  In file included from include/linux/mman.h:4:0,
                   from arch/arm/mm/init.c:15:
  include/linux/mm.h:1301:22: note: expected 'long unsigned int' but argument is of type 'void *'
   extern unsigned long free_reserved_area(unsigned long start, unsigned long end,

   mm/page_alloc.c: In function 'free_reserved_area':
>> mm/page_alloc.c:5134:3: warning: passing argument 1 of 'virt_to_phys' makes pointer from integer without a cast [enabled by default]
   In file included from arch/mips/include/asm/page.h:49:0,
                    from include/linux/mmzone.h:20,
                    from include/linux/gfp.h:4,
                    from include/linux/mm.h:8,
                    from mm/page_alloc.c:18:
   arch/mips/include/asm/io.h:119:29: note: expected 'const volatile void *' but argument is of type 'long unsigned int'
   mm/page_alloc.c: In function 'free_area_init_nodes':
   mm/page_alloc.c:5030:34: warning: array subscript is below array bounds [-Warray-bounds]

Also address some minor code review comments.

Signed-off-by: Jiang Liu 
Reported-by: Arnd Bergmann 
Cc: "H. Peter Anvin" 
Cc: "Michael S. Tsirkin" 
Cc: 
Cc: Catalin Marinas 
Cc: Chris Metcalf 
Cc: David Howells 
Cc: Geert Uytterhoeven 
Cc: Ingo Molnar 
Cc: Jeremy Fitzhardinge 
Cc: Jianguo Wu 
Cc: Joonsoo Kim 
Cc: Kamezawa Hiroyuki 
Cc: Konrad Rzeszutek Wilk 
Cc: Marek Szyprowski 
Cc: Mel Gorman 
Cc: Michel Lespinasse 
Cc: Minchan Kim 
Cc: Rik van Riel 
Cc: Rusty Russell 
Cc: Tang Chen 
Cc: Tejun Heo 
Cc: Thomas Gleixner 
Cc: Wen Congyang 
Cc: Will Deacon 
Cc: Yasuaki Ishimatsu 
Cc: Yinghai Lu 
Cc: Russell King 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/openrisc: use common help functions to free reserved pages

2013-04-29T22:54:30+00:00

Use common help functions to free reserved pages.
Also include  to avoid local declarations.

Signed-off-by: Jiang Liu 
Cc: Jonas Bonn 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

openrisc: update DTLB-miss handler last

2013-02-17T07:46:10+00:00

The self-modifying code that updates the TLB handler at start-up has
a subtle ordering requirement:  the DTLB handler must be the last thing
changed.

What I was seeing was the following:

i)   The DTLB handler was updated
ii)  The following printk caused a TLB miss and the look-up resulted
     in the page containing itlb_vector (0xc0000a00) being bounced from
     the TLB.
iii) The subsequent access to itlb_vector caused a TLB miss and reload
     of the page containing itlb_vector from the page tables.
iv)  But this reload of the page in iii) was being done by the "new"
     DTLB-miss handler which resulted (correctly) in the page flags being
     set to read-only; the subsequent write-access to itlb_vector thus
     resulted in a page (access) fault.

This is easily remedied if we ensure that the boot-time DTLB-miss handler
continues running until the very last bit of self-modifying code has been
executed.  This patch should ensure that the very last thing updated is the
DTLB-handler itself.

Signed-off-by: Jonas Bonn 
Acked-by: Julius Baxter 
Tested-by: Sebastian Macke

readahead: fault retry breaks mmap file read random detection

2012-10-09T07:22:47+00:00

.fault now can retry.  The retry can break state machine of .fault.  In
filemap_fault, if page is miss, ra->mmap_miss is increased.  In the second
try, since the page is in page cache now, ra->mmap_miss is decreased.  And
these are done in one fault, so we can't detect random mmap file access.

Add a new flag to indicate .fault is tried once.  In the second try, skip
ra->mmap_miss decreasing.  The filemap_fault state machine is ok with it.

I only tested x86, didn't test other archs, but looks the change for other
archs is obvious, but who knows :)

Signed-off-by: Shaohua Li 
Cc: Rik van Riel 
Cc: Wu Fengguang 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds