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ANDROID: Fix mmu_notifier imbalance

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SPF patchset introduced an mmu_notifier imbalance by adding a new exit
path that skips mmu_notifier_invalidate_range_only_end after calling
mmu_notifier_invalidate_range_start. This triggers a BUG in KVM driver
checking for mmu_notifier_count to remain balanced

Fixes: afeec97a8d ("FROMLIST: mm: prepare for FAULT_FLAG_SPECULATIVE")
Bug: 161210518
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: Ibe9d1f0903a23b48c9d733b81249b190e5321c2f
This commit is contained in:
Suren Baghdasaryan 2021-10-29 11:00:34 -07:00
parent 62f22f5c05
commit 6ad609468d
1 changed files with 3 additions and 1 deletions
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4
mm/memory.c
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@ -3159,7 +3159,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
*/ */
if (!pte_map_lock(vmf)) { if (!pte_map_lock(vmf)) {
ret = VM_FAULT_RETRY; ret = VM_FAULT_RETRY;
goto out_free_new; goto out_invalidate_end;
} }
if (likely(pte_same(*vmf->pte, vmf->orig_pte))) { if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
if (old_page) { if (old_page) {
@ -3247,6 +3247,8 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
put_page(old_page); put_page(old_page);
} }
return page_copied ? VM_FAULT_WRITE : 0; return page_copied ? VM_FAULT_WRITE : 0;
out_invalidate_end:
mmu_notifier_invalidate_range_only_end(&range);
out_free_new: out_free_new:
put_page(new_page); put_page(new_page);
out: out: