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FROMLIST: mm: enable speculative fault handling through do_anonymous_page()

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in x86 fault handler, only attempt spf if the vma is anonymous.

In do_handle_mm_fault(), let speculative page faults proceed as long
as they fall into anonymous vmas. This enables the speculative
handling code in __handle_mm_fault() and do_anonymous_page().

In handle_pte_fault(), if vmf->pte is set (the original pte was not
pte_none), catch speculative faults and return VM_FAULT_RETRY as
those cases are not implemented yet. Also assert that do_fault()
is not reached in the speculative case.

Signed-off-by: Michel Lespinasse <michel@lespinasse.org>
Link: https://lore.kernel.org/all/20220128131006.67712-20-michel@lespinasse.org/
Bug: 161210518
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I875106fcfa1084f570c2bf8f24a129bdce55316b
This commit is contained in:
Michel Lespinasse
2022-01-24 17:43:55 -08:00
committed by Todd Kjos
parent 31cf1fd564
commit c2b2abe724
2 changed files with 13 additions and 5 deletions
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2
arch/x86/mm/fault.c
View File

@@ -1334,7 +1334,7 @@ void do_user_addr_fault(struct pt_regs *regs,
goto spf_abort;
rcu_read_lock();
vma = __find_vma(mm, address);
if (!vma || vma->vm_start > address) {
if (!vma || vma->vm_start > address || !vma_is_anonymous(vma)) {
rcu_read_unlock();
goto spf_abort;
}

16
mm/memory.c
View File

@@ -4367,6 +4367,8 @@ static vm_fault_t do_fault(struct vm_fault *vmf)
struct mm_struct *vm_mm = vma->vm_mm;
vm_fault_t ret;
VM_BUG_ON(vmf->flags & FAULT_FLAG_SPECULATIVE);
/*
* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND
*/
@@ -4611,6 +4613,11 @@ static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
return do_fault(vmf);
}
if (vmf->flags & FAULT_FLAG_SPECULATIVE) {
pte_unmap(vmf->pte);
return VM_FAULT_RETRY;
}
if (!pte_present(vmf->orig_pte))
return do_swap_page(vmf);
@@ -4939,8 +4946,7 @@ vm_fault_t do_handle_mm_fault(struct vm_area_struct *vma,
{
vm_fault_t ret;
if (flags & FAULT_FLAG_SPECULATIVE)
return VM_FAULT_RETRY;
VM_BUG_ON((flags & FAULT_FLAG_SPECULATIVE) && !vma_is_anonymous(vma));
__set_current_state(TASK_RUNNING);
@@ -4962,10 +4968,12 @@ vm_fault_t do_handle_mm_fault(struct vm_area_struct *vma,
if (flags & FAULT_FLAG_USER)
mem_cgroup_enter_user_fault();
if (unlikely(is_vm_hugetlb_page(vma)))
if (unlikely(is_vm_hugetlb_page(vma))) {
VM_BUG_ON(flags & FAULT_FLAG_SPECULATIVE);
ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
else
} else {
ret = __handle_mm_fault(vma, address, flags, seq);
}
if (flags & FAULT_FLAG_USER) {
mem_cgroup_exit_user_fault();