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authorToshi Kani <toshi.kani@hpe.com>2015-12-22 17:54:23 -0700
committerThomas Gleixner <tglx@linutronix.de>2016-01-05 11:10:05 +0100
commitd9fe4fab11976e56b2e992980bf6ce948bdf02ac (patch)
treeefbf8627823ee26cbbc397d8aa7ba158a849eb31 /mm
parent9abb0ecdee69a2577560cc283368e490da974934 (diff)
x86/mm/pat: Add untrack_pfn_moved for mremap
mremap() with MREMAP_FIXED on a VM_PFNMAP range causes the following WARN_ON_ONCE() message in untrack_pfn(). WARNING: CPU: 1 PID: 3493 at arch/x86/mm/pat.c:985 untrack_pfn+0xbd/0xd0() Call Trace: [<ffffffff817729ea>] dump_stack+0x45/0x57 [<ffffffff8109e4b6>] warn_slowpath_common+0x86/0xc0 [<ffffffff8109e5ea>] warn_slowpath_null+0x1a/0x20 [<ffffffff8106a88d>] untrack_pfn+0xbd/0xd0 [<ffffffff811d2d5e>] unmap_single_vma+0x80e/0x860 [<ffffffff811d3725>] unmap_vmas+0x55/0xb0 [<ffffffff811d916c>] unmap_region+0xac/0x120 [<ffffffff811db86a>] do_munmap+0x28a/0x460 [<ffffffff811dec33>] move_vma+0x1b3/0x2e0 [<ffffffff811df113>] SyS_mremap+0x3b3/0x510 [<ffffffff817793ee>] entry_SYSCALL_64_fastpath+0x12/0x71 MREMAP_FIXED moves a pfnmap from old vma to new vma. untrack_pfn() is called with the old vma after its pfnmap page table has been removed, which causes follow_phys() to fail. The new vma has a new pfnmap to the same pfn & cache type with VM_PAT set. Therefore, we only need to clear VM_PAT from the old vma in this case. Add untrack_pfn_moved(), which clears VM_PAT from a given old vma. move_vma() is changed to call this function with the old vma when VM_PFNMAP is set. move_vma() then calls do_munmap(), and untrack_pfn() is a no-op since VM_PAT is cleared. Reported-by: Stas Sergeev <stsp@list.ru> Signed-off-by: Toshi Kani <toshi.kani@hpe.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Borislav Petkov <bp@suse.de> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/1450832064-10093-2-git-send-email-toshi.kani@hpe.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'mm')
-rw-r--r--mm/mremap.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/mm/mremap.c b/mm/mremap.c
index c25bc6268e46..de824e72c3e8 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -319,6 +319,10 @@ static unsigned long move_vma(struct vm_area_struct *vma,
hiwater_vm = mm->hiwater_vm;
vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
+ /* Tell pfnmap has moved from this vma */
+ if (unlikely(vma->vm_flags & VM_PFNMAP))
+ untrack_pfn_moved(vma);
+
if (do_munmap(mm, old_addr, old_len) < 0) {
/* OOM: unable to split vma, just get accounts right */
vm_unacct_memory(excess >> PAGE_SHIFT);