linux.git/mm/huge_memory.c, branch v4.10

mm/huge_memory.c: respect FOLL_FORCE/FOLL_COW for thp

2017-01-25T00:26:14+00:00

In commit 19be0eaffa3a ("mm: remove gup_flags FOLL_WRITE games from
__get_user_pages()"), the mm code was changed from unsetting FOLL_WRITE
after a COW was resolved to setting the (newly introduced) FOLL_COW
instead.  Simultaneously, the check in gup.c was updated to still allow
writes with FOLL_FORCE set if FOLL_COW had also been set.

However, a similar check in huge_memory.c was forgotten.  As a result,
remote memory writes to ro regions of memory backed by transparent huge
pages cause an infinite loop in the kernel (handle_mm_fault sets
FOLL_COW and returns 0 causing a retry, but follow_trans_huge_pmd bails
out immidiately because `(flags & FOLL_WRITE) && !pmd_write(*pmd)` is
true.

While in this state the process is stil SIGKILLable, but little else
works (e.g.  no ptrace attach, no other signals).  This is easily
reproduced with the following code (assuming thp are set to always):

    #include 
    #include 
    #include 
    #include 
    #include 
    #include 
    #include 
    #include 
    #include 
    #include 

    #define TEST_SIZE 5 * 1024 * 1024

    int main(void) {
      int status;
      pid_t child;
      int fd = open("/proc/self/mem", O_RDWR);
      void *addr = mmap(NULL, TEST_SIZE, PROT_READ,
                        MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
      assert(addr != MAP_FAILED);
      pid_t parent_pid = getpid();
      if ((child = fork()) == 0) {
        void *addr2 = mmap(NULL, TEST_SIZE, PROT_READ | PROT_WRITE,
                           MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
        assert(addr2 != MAP_FAILED);
        memset(addr2, 'a', TEST_SIZE);
        pwrite(fd, addr2, TEST_SIZE, (uintptr_t)addr);
        return 0;
      }
      assert(child == waitpid(child, &status, 0));
      assert(WIFEXITED(status) && WEXITSTATUS(status) == 0);
      return 0;
    }

Fix this by updating follow_trans_huge_pmd in huge_memory.c analogously
to the update in gup.c in the original commit.  The same pattern exists
in follow_devmap_pmd.  However, we should not be able to reach that
check with FOLL_COW set, so add WARN_ONCE to make sure we notice if we
ever do.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20170106015025.GA38411@juliacomputing.com
Signed-off-by: Keno Fischer 
Acked-by: Kirill A. Shutemov 
Cc: Greg Thelen 
Cc: Nicholas Piggin 
Cc: Willy Tarreau 
Cc: Oleg Nesterov 
Cc: Kees Cook 
Cc: Andy Lutomirski 
Cc: Michal Hocko 
Cc: Hugh Dickins 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: pmd dirty emulation in page fault handler

2017-01-11T02:31:55+00:00

Andreas reported [1] made a test in jemalloc hang in THP mode in arm64:

  http://lkml.kernel.org/r/mvmmvfy37g1.fsf@hawking.suse.de

The problem is currently page fault handler doesn't supports dirty bit
emulation of pmd for non-HW dirty-bit architecture so that application
stucks until VM marked the pmd dirty.

How the emulation work depends on the architecture.  In case of arm64,
when it set up pte firstly, it sets pte PTE_RDONLY to get a chance to
mark the pte dirty via triggering page fault when store access happens.
Once the page fault occurs, VM marks the pmd dirty and arch code for
setting pmd will clear PTE_RDONLY for application to proceed.

IOW, if VM doesn't mark the pmd dirty, application hangs forever by
repeated fault(i.e., store op but the pmd is PTE_RDONLY).

This patch enables pmd dirty-bit emulation for those architectures.

[1] b8d3c4c3009d, mm/huge_memory.c: don't split THP page when MADV_FREE syscall is called

Fixes: b8d3c4c3009d ("mm/huge_memory.c: don't split THP page when MADV_FREE syscall is called")
Link: http://lkml.kernel.org/r/1482506098-6149-1-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim 
Reported-by: Andreas Schwab 
Tested-by: Andreas Schwab 
Acked-by: Kirill A. Shutemov 
Acked-by: Michal Hocko 
Cc: Jason Evans 
Cc: Will Deacon 
Cc: Catalin Marinas 
Cc:  [4.5+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: get rid of __GFP_OTHER_NODE

2017-01-11T02:31:55+00:00

The flag was introduced by commit 78afd5612deb ("mm: add
__GFP_OTHER_NODE flag") to allow proper accounting of remote node
allocations done by kernel daemons on behalf of a process - e.g.
khugepaged.

After "mm: fix remote numa hits statistics" we do not need and actually
use the flag so we can safely remove it because all allocations which
are satisfied from their "home" node are accounted properly.

[mhocko@suse.com: fix build]
Link: http://lkml.kernel.org/r/20170106122225.GK5556@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/20170102153057.9451-3-mhocko@kernel.org
Signed-off-by: Michal Hocko 
Acked-by: Mel Gorman 
Acked-by: Vlastimil Babka 
Cc: Michal Hocko 
Cc: Johannes Weiner 
Cc: Joonsoo Kim 
Cc: Taku Izumi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: join struct fault_env and vm_fault

2016-12-15T00:04:09+00:00

Currently we have two different structures for passing fault information
around - struct vm_fault and struct fault_env.  DAX will need more
information in struct vm_fault to handle its faults so the content of
that structure would become event closer to fault_env.  Furthermore it
would need to generate struct fault_env to be able to call some of the
generic functions.  So at this point I don't think there's much use in
keeping these two structures separate.  Just embed into struct vm_fault
all that is needed to use it for both purposes.

Link: http://lkml.kernel.org/r/1479460644-25076-2-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara 
Acked-by: Kirill A. Shutemov 
Cc: Ross Zwisler 
Cc: Dan Williams 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: make transparent hugepage size public

2016-12-13T02:55:09+00:00

Test programs want to know the size of a transparent hugepage.  While it
is commonly the same as the size of a hugetlbfs page (shown as
Hugepagesize in /proc/meminfo), that is not always so: powerpc
implements transparent hugepages in a different way from hugetlbfs
pages, so it's coincidence when their sizes are the same; and x86 and
others can support more than one hugetlbfs page size.

Add /sys/kernel/mm/transparent_hugepage/hpage_pmd_size to show the THP
size in bytes - it's the same for Anonymous and Shmem hugepages.  Call
it hpage_pmd_size (after HPAGE_PMD_SIZE) rather than hpage_size, in case
some transparent support for pud and pgd pages is added later.

Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1612052200290.13021@eggly.anvils
Signed-off-by: Hugh Dickins 
Acked-by: Michal Hocko 
Acked-by: Vlastimil Babka 
Cc: Greg Thelen 
Cc: David Rientjes 
Cc: "Kirill A. Shutemov" 
Cc: Andrea Arcangeli 
Cc: "Aneesh Kumar K.V" 
Cc: Dave Hansen 
Cc: Dan Williams 
Cc: Jan Kara 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: THP page cache support for ppc64

2016-12-13T02:55:08+00:00

Add arch specific callback in the generic THP page cache code that will
deposit and withdarw preallocated page table.  Archs like ppc64 use this
preallocated table to store the hash pte slot information.

Testing:
kernel build of the patch series on tmpfs mounted with option huge=always

The related thp stat:
thp_fault_alloc 72939
thp_fault_fallback 60547
thp_collapse_alloc 603
thp_collapse_alloc_failed 0
thp_file_alloc 253763
thp_file_mapped 4251
thp_split_page 51518
thp_split_page_failed 1
thp_deferred_split_page 73566
thp_split_pmd 665
thp_zero_page_alloc 3
thp_zero_page_alloc_failed 0

[akpm@linux-foundation.org: remove unneeded parentheses, per Kirill]
Link: http://lkml.kernel.org/r/20161113150025.17942-2-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V 
Acked-by: Kirill A. Shutemov 
Cc: Michael Ellerman 
Cc: Benjamin Herrenschmidt 
Cc: Michael Neuling 
Cc: Paul Mackerras 
Cc: Balbir Singh 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: move vma_is_anonymous check within pmd_move_must_withdraw

2016-12-13T02:55:08+00:00

Independent of whether the vma is for anonymous memory, some arches like
ppc64 would like to override pmd_move_must_withdraw().

One option is to encapsulate the vma_is_anonymous() check for general
architectures inside pmd_move_must_withdraw() so that is always called
and architectures that need unconditional overriding can override this
function.  ppc64 needs to override the function when the MMU is
configured to use hash PTE's.

[bsingharora@gmail.com: reworked changelog]
Link: http://lkml.kernel.org/r/20161113150025.17942-1-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V 
Acked-by: Kirill A. Shutemov 
Acked-by: Michael Ellerman  (powerpc)
Cc: Benjamin Herrenschmidt 
Cc: Michael Neuling 
Cc: Paul Mackerras 
Cc: Balbir Singh 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: add tlb_remove_check_page_size_change to track page size change

2016-12-13T02:55:07+00:00

With commit e77b0852b551 ("mm/mmu_gather: track page size with mmu
gather and force flush if page size change") we added the ability to
force a tlb flush when the page size change in a mmu_gather loop.  We
did that by checking for a page size change every time we added a page
to mmu_gather for lazy flush/remove.  We can improve that by moving the
page size change check early and not doing it every time we add a page.

This also helps us to do tlb flush when invalidating a range covering
dax mapping.  Wrt dax mapping we don't have a backing struct page and
hence we don't call tlb_remove_page, which earlier forced the tlb flush
on page size change.  Moving the page size change check earlier means we
will do the same even for dax mapping.

We also avoid doing this check on architecture other than powerpc.

In a later patch we will remove page size check from tlb_remove_page().

Link: http://lkml.kernel.org/r/20161026084839.27299-5-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V 
Cc: "Kirill A. Shutemov" 
Cc: Dan Williams 
Cc: Ross Zwisler 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: use the correct page size when removing the page

2016-12-13T02:55:07+00:00

We are removing a pmd hugepage here.  Use the correct page size.

Link: http://lkml.kernel.org/r/20161026084839.27299-2-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V 
Cc: "Kirill A. Shutemov" 
Cc: Dan Williams 
Cc: Ross Zwisler 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'mm-pat-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2016-12-12T19:14:52+00:00

Pull mm/PAT cleanup from Ingo Molnar:
 "A single cleanup for a generic interface that was originally
  introduced for PAT"

* 'mm-pat-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/pat, mm: Make track_pfn_insert() return void