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commit ba422731316dde1e22dcc84b83c7349dc0ce1c3c
parent 4064e47c82810586975b4304b105056389beaa06
Author: Sean Christopherson <sean.j.christopherson@intel.com>
Date:   Wed,  9 Jan 2019 16:51:17 -0800

mm/mmu_notifier: mm/rmap.c: Fix a mmu_notifier range bug in try_to_unmap_one

The conversion to use a structure for mmu_notifier_invalidate_range_*()
unintentionally changed the usage in try_to_unmap_one() to init the
'struct mmu_notifier_range' with vma->vm_start instead of @address,
i.e. it invalidates the wrong address range.  Revert to the correct
address range.

Manifests as KVM use-after-free WARNINGs and subsequent "BUG: Bad page
state in process X" errors when reclaiming from a KVM guest due to KVM
removing the wrong pages from its own mappings.

Reported-by: leozinho29_eu@hotmail.com
Reported-by: Mike Galbraith <efault@gmx.de>
Reported-and-tested-by: Adam Borowski <kilobyte@angband.pl>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: Pankaj gupta <pagupta@redhat.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Ross Zwisler <zwisler@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Felix Kuehling <felix.kuehling@amd.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Fixes: ac46d4f3c432 ("mm/mmu_notifier: use structure for invalidate_range_start/end calls v2")
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Mmm/rmap.c | 4++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/rmap.c b/mm/rmap.c @@ -1371,8 +1371,8 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, * Note that the page can not be free in this function as call of * try_to_unmap() must hold a reference on the page. */ - mmu_notifier_range_init(&range, vma->vm_mm, vma->vm_start, - min(vma->vm_end, vma->vm_start + + mmu_notifier_range_init(&range, vma->vm_mm, address, + min(vma->vm_end, address + (PAGE_SIZE << compound_order(page)))); if (PageHuge(page)) { /*