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| author | Youquan Song <youquan.song@intel.com> | 2011-12-08 14:34:18 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-12-21 12:58:22 -0800 |
| commit | 7f37071e9df2344a7d7d066235ec72a0d1a4b013 (patch) | |
| tree | 159499fa82f3aa12ee6539c7f5f7d5d507d693f8 | |
| parent | 75aaef5468ceb118aa55825cf6a52d60d09dfde0 (diff) | |
| download | lwn-7f37071e9df2344a7d7d066235ec72a0d1a4b013.tar.gz lwn-7f37071e9df2344a7d7d066235ec72a0d1a4b013.zip | |
thp: set compound tail page _count to zero
commit 58a84aa92723d1ac3e1cc4e3b0ff49291663f7e1 upstream.
Commit 70b50f94f1644 ("mm: thp: tail page refcounting fix") keeps all
page_tail->_count zero at all times. But the current kernel does not
set page_tail->_count to zero if a 1GB page is utilized. So when an
IOMMU 1GB page is used by KVM, it wil result in a kernel oops because a
tail page's _count does not equal zero.
kernel BUG at include/linux/mm.h:386!
invalid opcode: 0000 [#1] SMP
Call Trace:
gup_pud_range+0xb8/0x19d
get_user_pages_fast+0xcb/0x192
? trace_hardirqs_off+0xd/0xf
hva_to_pfn+0x119/0x2f2
gfn_to_pfn_memslot+0x2c/0x2e
kvm_iommu_map_pages+0xfd/0x1c1
kvm_iommu_map_memslots+0x7c/0xbd
kvm_iommu_map_guest+0xaa/0xbf
kvm_vm_ioctl_assigned_device+0x2ef/0xa47
kvm_vm_ioctl+0x36c/0x3a2
do_vfs_ioctl+0x49e/0x4e4
sys_ioctl+0x5a/0x7c
system_call_fastpath+0x16/0x1b
RIP gup_huge_pud+0xf2/0x159
Signed-off-by: Youquan Song <youquan.song@intel.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | mm/hugetlb.c | 1 | ||||
| -rw-r--r-- | mm/page_alloc.c | 2 |
2 files changed, 2 insertions, 1 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index bb28a5f9db8d..73f17c0293c0 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -576,6 +576,7 @@ static void prep_compound_gigantic_page(struct page *page, unsigned long order) __SetPageHead(page); for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) { __SetPageTail(p); + set_page_count(p, 0); p->first_page = page; } } diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 6e8ecb6e021c..2548891f16fc 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -355,8 +355,8 @@ void prep_compound_page(struct page *page, unsigned long order) __SetPageHead(page); for (i = 1; i < nr_pages; i++) { struct page *p = page + i; - __SetPageTail(p); + set_page_count(p, 0); p->first_page = page; } } |