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FROMLIST: mm: implement speculative handling in do_anonymous_page()

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Change do_anonymous_page() to handle the speculative case.
This involves aborting speculative faults if they have to allocate a new
anon_vma, and using pte_map_lock() instead of pte_offset_map_lock()
to complete the page fault.

Signed-off-by: Michel Lespinasse <michel@lespinasse.org>
Link: https://lore.kernel.org/all/20220128131006.67712-19-michel@lespinasse.org/
Bug: 161210518
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I5ad955323faabc142c21f62415db039ac889066a
This commit is contained in:
Michel Lespinasse
2022-01-24 17:43:55 -08:00
committed by Todd Kjos
parent 6e6766ab76
commit 31cf1fd564
1 changed files with 13 additions and 4 deletions
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17
mm/memory.c
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@@ -3839,8 +3839,12 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
vma->vm_page_prot));
} else {
/* Allocate our own private page. */
if (unlikely(anon_vma_prepare(vma)))
goto oom;
if (unlikely(!vma->anon_vma)) {
if (vmf->flags & FAULT_FLAG_SPECULATIVE)
return VM_FAULT_RETRY;
if (__anon_vma_prepare(vma))
goto oom;
}
page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
if (!page)
goto oom;
@@ -3862,8 +3866,10 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
entry = pte_mkwrite(pte_mkdirty(entry));
}
vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
&vmf->ptl);
if (!pte_map_lock(vmf)) {
ret = VM_FAULT_RETRY;
goto release;
}
if (!pte_none(*vmf->pte)) {
update_mmu_tlb(vma, vmf->address, vmf->pte);
goto unlock;
@@ -3878,6 +3884,8 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
pte_unmap_unlock(vmf->pte, vmf->ptl);
if (page)
put_page(page);
if (vmf->flags & FAULT_FLAG_SPECULATIVE)
return VM_FAULT_RETRY;
return handle_userfault(vmf, VM_UFFD_MISSING);
}
@@ -3895,6 +3903,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
return 0;
unlock:
pte_unmap_unlock(vmf->pte, vmf->ptl);
release:
if (page)
put_page(page);
return ret;