linux-toradex.git/mm/memory.c, branch v3.14.34

mm: make copy_pte_range static again

2015-01-30T01:40:52+00:00

commit 21bda264f4243f61dfcc485174055f12ad0530b4 upstream.

Commit 71e3aac0724f ("thp: transparent hugepage core") adds
copy_pte_range prototype to huge_mm.h.  I'm not sure why (or if) this
function have been used outside of memory.c, but it currently isn't.
This patch makes copy_pte_range() static again.

Signed-off-by: Jerome Marchand 
Acked-by: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Mel Gorman 
Signed-off-by: Greg Kroah-Hartman

mm/memory.c: use entry = ACCESS_ONCE(*pte) in handle_pte_fault()

2015-01-30T01:40:52+00:00

commit c0d73261f5c1355a35b8b40e871d31578ce0c044 upstream.

Use ACCESS_ONCE() in handle_pte_fault() when getting the entry or
orig_pte upon which all subsequent decisions and pte_same() tests will
be made.

I have no evidence that its lack is responsible for the mm/filemap.c:202
BUG_ON(page_mapped(page)) in __delete_from_page_cache() found by
trinity, and I am not optimistic that it will fix it.  But I have found
no other explanation, and ACCESS_ONCE() here will surely not hurt.

If gcc does re-access the pte before passing it down, then that would be
disastrous for correct page fault handling, and certainly could explain
the page_mapped() BUGs seen (concurrent fault causing page to be mapped
in a second time on top of itself: mapcount 2 for a single pte).

Signed-off-by: Hugh Dickins 
Cc: Sasha Levin 
Cc: Linus Torvalds 
Cc: "Kirill A. Shutemov" 
Cc: Konstantin Khlebnikov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Mel Gorman 
Signed-off-by: Greg Kroah-Hartman

mm: propagate error from stack expansion even for guard page

2015-01-16T14:59:35+00:00

commit fee7e49d45149fba60156f5b59014f764d3e3728 upstream.

Jay Foad reports that the address sanitizer test (asan) sometimes gets
confused by a stack pointer that ends up being outside the stack vma
that is reported by /proc/maps.

This happens due to an interaction between RLIMIT_STACK and the guard
page: when we do the guard page check, we ignore the potential error
from the stack expansion, which effectively results in a missing guard
page, since the expected stack expansion won't have been done.

And since /proc/maps explicitly ignores the guard page (commit
d7824370e263: "mm: fix up some user-visible effects of the stack guard
page"), the stack pointer ends up being outside the reported stack area.

This is the minimal patch: it just propagates the error.  It also
effectively makes the guard page part of the stack limit, which in turn
measn that the actual real stack is one page less than the stack limit.

Let's see if anybody notices.  We could teach acct_stack_growth() to
allow an extra page for a grow-up/grow-down stack in the rlimit test,
but I don't want to add more complexity if it isn't needed.

Reported-and-tested-by: Jay Foad 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm: fix swapoff hang after page migration and fork

2014-12-16T17:34:26+00:00

commit 2022b4d18a491a578218ce7a4eca8666db895a73 upstream.

I've been seeing swapoff hangs in recent testing: it's cycling around
trying unsuccessfully to find an mm for some remaining pages of swap.

I have been exercising swap and page migration more heavily recently,
and now notice a long-standing error in copy_one_pte(): it's trying to
add dst_mm to swapoff's mmlist when it finds a swap entry, but is doing
so even when it's a migration entry or an hwpoison entry.

Which wouldn't matter much, except it adds dst_mm next to src_mm,
assuming src_mm is already on the mmlist: which may not be so.  Then if
pages are later swapped out from dst_mm, swapoff won't be able to find
where to replace them.

There's already a !non_swap_entry() test for stats: move that up before
the swap_duplicate() and the addition to mmlist.

Signed-off-by: Hugh Dickins 
Cc: Kelley Nielsen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm: softdirty: keep bit when zapping file pte

2014-10-05T21:52:21+00:00

commit dbab31aa2ceec2d201966fa0b552f151310ba5f4 upstream.

This fixes the same bug as b43790eedd31 ("mm: softdirty: don't forget to
save file map softdiry bit on unmap") and 9aed8614af5a ("mm/memory.c:
don't forget to set softdirty on file mapped fault") where the return
value of pte_*mksoft_dirty was being ignored.

To be sure that no other pte/pmd "mk" function return values were being
ignored, I annotated the functions in arch/x86/include/asm/pgtable.h
with __must_check and rebuilt.

The userspace effect of this bug is that the softdirty mark might be
lost if a file mapped pte get zapped.

Signed-off-by: Peter Feiner 
Acked-by: Cyrill Gorcunov 
Cc: Pavel Emelyanov 
Cc: Jamie Liu 
Cc: Hugh Dickins 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm/numa: Remove BUG_ON() in __handle_mm_fault()

2014-07-09T18:18:29+00:00

commit 107437febd495a50e2cd09c81bbaa84d30e57b07 upstream.

Changing PTEs and PMDs to pte_numa & pmd_numa is done with the
mmap_sem held for reading, which means a pmd can be instantiated
and turned into a numa one while __handle_mm_fault() is examining
the value of old_pmd.

If that happens, __handle_mm_fault() should just return and let
the page fault retry, instead of throwing an oops. This is
handled by the test for pmd_trans_huge(*pmd) below.

Signed-off-by: Rik van Riel 
Reviewed-by: Naoya Horiguchi 
Reported-by: Sunil Pandey 
Signed-off-by: Peter Zijlstra 
Cc: Andrew Morton 
Cc: Johannes Weiner 
Cc: Kirill A. Shutemov 
Cc: Linus Torvalds 
Cc: Mel Gorman 
Cc: linux-mm@kvack.org
Cc: lwoodman@redhat.com
Cc: dave.hansen@intel.com
Link: http://lkml.kernel.org/r/20140429153615.2d72098e@annuminas.surriel.com
Signed-off-by: Ingo Molnar 
Patrick McLean 
Signed-off-by: Greg Kroah-Hartman

mm: make fixup_user_fault() check the vma access rights too

2014-06-07T17:28:08+00:00

commit 1b17844b29ae042576bea588164f2f1e9590a8bc upstream.

fixup_user_fault() is used by the futex code when the direct user access
fails, and the futex code wants it to either map in the page in a usable
form or return an error.  It relied on handle_mm_fault() to map the
page, and correctly checked the error return from that, but while that
does map the page, it doesn't actually guarantee that the page will be
mapped with sufficient permissions to be then accessed.

So do the appropriate tests of the vma access rights by hand.

[ Side note: arguably handle_mm_fault() could just do that itself, but
  we have traditionally done it in the caller, because some callers -
  notably get_user_pages() - have been able to access pages even when
  they are mapped with PROT_NONE.  Maybe we should re-visit that design
  decision, but in the meantime this is the minimal patch. ]

Found by Dave Jones running his trinity tool.

Reported-by: Dave Jones 
Acked-by: Hugh Dickins 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

mm, thp: fix infinite loop on memcg OOM

2014-02-25T23:25:44+00:00

Masayoshi Mizuma reported a bug with the hang of an application under
the memcg limit.  It happens on write-protection fault to huge zero page

If we successfully allocate a huge page to replace zero page but hit the
memcg limit we need to split the zero page with split_huge_page_pmd()
and fallback to small pages.

The other part of the problem is that VM_FAULT_OOM has special meaning
in do_huge_pmd_wp_page() context.  __handle_mm_fault() expects the page
to be split if it sees VM_FAULT_OOM and it will will retry page fault
handling.  This causes an infinite loop if the page was not split.

do_huge_pmd_wp_zero_page_fallback() can return VM_FAULT_OOM if it failed
to allocate one small page, so fallback to small pages will not help.

The solution for this part is to replace VM_FAULT_OOM with
VM_FAULT_FALLBACK is fallback required.

Signed-off-by: Kirill A. Shutemov 
Reported-by: Masayoshi Mizuma 
Reviewed-by: Michal Hocko 
Cc: Johannes Weiner 
Cc: Andrea Arcangeli 
Cc: David Rientjes 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, hwpoison: release page on PageHWPoison() in __do_fault()

2014-02-25T23:25:42+00:00

It seems we forget to release page after detecting HW error.

Signed-off-by: Kirill A. Shutemov 
Cc: Mel Gorman 
Cc: Rik van Riel 
Cc: Andi Kleen 
Cc: Matthew Wilcox 
Cc: Dave Hansen 
Cc: Naoya Horiguchi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE

2014-01-24T00:36:50+00:00

Most of the VM_BUG_ON assertions are performed on a page.  Usually, when
one of these assertions fails we'll get a BUG_ON with a call stack and
the registers.

I've recently noticed based on the requests to add a small piece of code
that dumps the page to various VM_BUG_ON sites that the page dump is
quite useful to people debugging issues in mm.

This patch adds a VM_BUG_ON_PAGE(cond, page) which beyond doing what
VM_BUG_ON() does, also dumps the page before executing the actual
BUG_ON.

[akpm@linux-foundation.org: fix up includes]
Signed-off-by: Sasha Levin 
Cc: "Kirill A. Shutemov" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds