linux/arch/x86/mm
Naoya Horiguchi cbef8478be mm/hugetlb: pmd_huge() returns true for non-present hugepage
Migrating hugepages and hwpoisoned hugepages are considered as non-present
hugepages, and they are referenced via migration entries and hwpoison
entries in their page table slots.

This behavior causes race condition because pmd_huge() doesn't tell
non-huge pages from migrating/hwpoisoned hugepages.  follow_page_mask() is
one example where the kernel would call follow_page_pte() for such
hugepage while this function is supposed to handle only normal pages.

To avoid this, this patch makes pmd_huge() return true when pmd_none() is
true *and* pmd_present() is false.  We don't have to worry about mixing up
non-present pmd entry with normal pmd (pointing to leaf level pte entry)
because pmd_present() is true in normal pmd.

The same race condition could happen in (x86-specific) gup_pmd_range(),
where this patch simply adds pmd_present() check instead of pmd_huge().
This is because gup_pmd_range() is fast path.  If we have non-present
hugepage in this function, we will go into gup_huge_pmd(), then return 0
at flag mask check, and finally fall back to the slow path.

Fixes: 290408d4a2 ("hugetlb: hugepage migration core")
Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: <stable@vger.kernel.org>	[2.6.36+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-11 17:06:01 -08:00
..
kmemcheck x86: Replace __get_cpu_var uses 2014-08-26 13:45:49 -04:00
amdtopology.c x86/mm/numa: Simplify some bit mangling 2013-04-10 19:06:26 +02:00
dump_pagetables.c Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-10 13:59:34 -08:00
extable.c x86, extable: Switch to relative exception table entries 2012-04-20 17:22:34 -07:00
fault.c vm: add VM_FAULT_SIGSEGV handling support 2015-01-29 10:51:32 -08:00
gup.c mm/hugetlb: pmd_huge() returns true for non-present hugepage 2015-02-11 17:06:01 -08:00
highmem_32.c mm: accurately calculate zone->managed_pages for highmem zones 2013-07-03 16:07:33 -07:00
hugetlbpage.c mm/hugetlb: pmd_huge() returns true for non-present hugepage 2015-02-11 17:06:01 -08:00
init_32.c x86: remove the Xen-specific _PAGE_IOMAP PTE flag 2014-09-23 13:36:20 +00:00
init_64.c Merge branch 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-10 14:24:20 -08:00
init.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2015-02-10 18:57:15 -08:00
iomap_32.c x86: Use new cache mode type in mm/iomap_32.c 2014-11-16 11:04:25 +01:00
ioremap.c Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-12-10 13:59:34 -08:00
kmmio.c x86: Delete non-required instances of include <linux/init.h> 2014-01-06 21:25:18 -08:00
Makefile x86, mpx: Add MPX-specific mmap interface 2014-11-18 00:58:53 +01:00
memtest.c x86/mm: memblock: switch to use NUMA_NO_NODE 2014-01-21 16:19:47 -08:00
mm_internal.h x86: Enable PAT to use cache mode translation tables 2014-11-16 11:04:26 +01:00
mmap.c x86/mm: Apply the section attribute to the variable, not its type 2014-09-09 07:13:39 +02:00
mmio-mod.c x86: delete __cpuinit usage from all x86 files 2013-07-14 19:36:56 -04:00
mpx.c x86, mpx: Explicitly disable 32-bit MPX support on 64-bit kernels 2015-01-22 21:11:06 +01:00
numa_32.c x86: Fix the initialization of physnode_map 2014-02-01 22:15:51 -08:00
numa_64.c x86, mm: kill numa_free_all_bootmem() 2012-11-17 11:59:47 -08:00
numa_emulation.c x86: delete __cpuinit usage from all x86 files 2013-07-14 19:36:56 -04:00
numa_internal.h x86-32, mm: Rip out x86_32 NUMA remapping code 2013-01-31 14:12:30 -08:00
numa.c Merge branch 'akpm' (patches from Andrew Morton) 2014-10-14 03:54:50 +02:00
pageattr-test.c x86: define _PAGE_NUMA by reusing software bits on the PMD and PTE levels 2014-06-04 16:53:55 -07:00
pageattr.c xen: additional features for 3.19-rc0 2014-12-16 13:23:03 -08:00
pat_internal.h x86: Use new cache mode type in memtype related functions 2014-11-16 11:04:26 +01:00
pat_rbtree.c x86: Use new cache mode type in memtype related functions 2014-11-16 11:04:26 +01:00
pat.c x86: Don't rely on VMWare emulating PAT MSR correctly 2015-01-20 14:33:45 +01:00
pf_in.c x86: Eliminate various 'set but not used' warnings 2011-05-21 19:10:33 +02:00
pf_in.h
pgtable_32.c x86: Remove set_pmd_pfn 2014-09-01 10:15:31 +02:00
pgtable.c Merge branch 'x86/vdso' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into next 2014-06-05 08:05:29 -07:00
physaddr.c x86, mm: Make DEBUG_VIRTUAL work earlier in boot 2013-01-25 16:33:22 -08:00
physaddr.h
setup_nx.c x86: delete __cpuinit usage from all x86 files 2013-07-14 19:36:56 -04:00
srat.c x86/mm: Avoid duplicated pxm_to_node() calls 2014-02-09 15:32:31 +01:00
testmmiotrace.c x86, kmmio/mmiotrace: Fix double free of kmmio_fault_pages 2010-06-18 11:30:09 +02:00
tlb.c x86/mm: Fix sparse 'tlb_single_page_flush_ceiling' warning and make the variable read-mostly 2014-08-10 09:07:18 +02:00