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Commit 896469cc authored by Laurent Dufour's avatar Laurent Dufour Committed by Vinayak Menon
Browse files

mm: cache some VMA fields in the vm_fault structure 



When handling speculative page fault, the vma->vm_flags and
vma->vm_page_prot fields are read once the page table lock is released. So
there is no more guarantee that these fields would not change in our back.
They will be saved in the vm_fault structure before the VMA is checked for
changes.

This patch also set the fields in hugetlb_no_page() and
__collapse_huge_page_swapin even if it is not need for the callee.

Signed-off-by: default avatarLaurent Dufour <ldufour@linux.vnet.ibm.com>
Change-Id: I9821f02ea32ef220b57b8bfd817992bbf71bbb1d
Patch-mainline: linux-mm @ Tue, 17 Apr 2018 16:33:18
[vinmenon@codeaurora.org: trivial merge conflict fixes]
Signed-off-by: default avatarVinayak Menon <vinmenon@codeaurora.org>
parent 39bb6bae

include/linux/mm.h

+8 −2
Original line number Diff line number Diff line
@@ -350,6 +350,12 @@ struct vm_fault { 
					 * page table to avoid allocation from

					 * atomic context.

					 */

	/*

	 * These entries are required when handling speculative page fault.

	 * This way the page handling is done using consistent field values.

	 */

	unsigned long vma_flags;

	pgprot_t vma_page_prot;

};



/* page entry size for vm->huge_fault() */
@@ -668,9 +674,9 @@ void free_compound_page(struct page *page); 
 * pte_mkwrite.  But get_user_pages can cause write faults for mappings

 * that do not have writing enabled, when used by access_process_vm.

 */

static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma)

static inline pte_t maybe_mkwrite(pte_t pte, unsigned long vma_flags)

{

	if (likely(vma->vm_flags & VM_WRITE))

	if (likely(vma_flags & VM_WRITE))

		pte = pte_mkwrite(pte);

	return pte;

}

mm/huge_memory.c

+3 −3
Original line number Diff line number Diff line
@@ -1187,8 +1187,8 @@ static int do_huge_pmd_wp_page_fallback(struct vm_fault *vmf, pmd_t orig_pmd, 


	for (i = 0; i < HPAGE_PMD_NR; i++, haddr += PAGE_SIZE) {

		pte_t entry;

		entry = mk_pte(pages[i], vma->vm_page_prot);

		entry = maybe_mkwrite(pte_mkdirty(entry), vma);

		entry = mk_pte(pages[i], vmf->vma_page_prot);

		entry = maybe_mkwrite(pte_mkdirty(entry), vmf->vma_flags);

		memcg = (void *)page_private(pages[i]);

		set_page_private(pages[i], 0);

		page_add_new_anon_rmap(pages[i], vmf->vma, haddr, false);
@@ -2114,7 +2114,7 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, 
				entry = pte_swp_mksoft_dirty(entry);

		} else {

			entry = mk_pte(page + i, READ_ONCE(vma->vm_page_prot));

			entry = maybe_mkwrite(entry, vma);

			entry = maybe_mkwrite(entry, vma->vm_flags);

			if (!write)

				entry = pte_wrprotect(entry);

			if (!young)

mm/hugetlb.c

+2 −0
Original line number Diff line number Diff line
@@ -3692,6 +3692,8 @@ static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma, 
				.vma = vma,

				.address = address,

				.flags = flags,

				.vma_flags = vma->vm_flags,

				.vma_page_prot = vma->vm_page_prot,

				/*

				 * Hard to debug if it ends up being

				 * used by a callee that assumes

mm/khugepaged.c

+2 −0
Original line number Diff line number Diff line
@@ -887,6 +887,8 @@ static bool __collapse_huge_page_swapin(struct mm_struct *mm, 
		.flags = FAULT_FLAG_ALLOW_RETRY,

		.pmd = pmd,

		.pgoff = linear_page_index(vma, address),

		.vma_flags = vma->vm_flags,

		.vma_page_prot = vma->vm_page_prot,

	};



	/* we only decide to swapin, if there is enough young ptes */

mm/memory.c

+26 −24
Original line number Diff line number Diff line
@@ -1822,7 +1822,7 @@ static int insert_pfn(struct vm_area_struct *vma, unsigned long addr, 
out_mkwrite:

	if (mkwrite) {

		entry = pte_mkyoung(entry);

		entry = maybe_mkwrite(pte_mkdirty(entry), vma);

		entry = maybe_mkwrite(pte_mkdirty(entry), vma->vm_flags);

	}



	set_pte_at(mm, addr, pte, entry);
@@ -2454,7 +2454,7 @@ static inline void wp_page_reuse(struct vm_fault *vmf) 


	flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));

	entry = pte_mkyoung(vmf->orig_pte);

	entry = maybe_mkwrite(pte_mkdirty(entry), vma);

	entry = maybe_mkwrite(pte_mkdirty(entry), vmf->vma_flags);

	if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))

		update_mmu_cache(vma, vmf->address, vmf->pte);

	pte_unmap_unlock(vmf->pte, vmf->ptl);
@@ -2530,8 +2530,8 @@ static int wp_page_copy(struct vm_fault *vmf) 
			inc_mm_counter_fast(mm, MM_ANONPAGES);

		}

		flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));

		entry = mk_pte(new_page, vma->vm_page_prot);

		entry = maybe_mkwrite(pte_mkdirty(entry), vma);

		entry = mk_pte(new_page, vmf->vma_page_prot);

		entry = maybe_mkwrite(pte_mkdirty(entry), vmf->vma_flags);

		/*

		 * Clear the pte entry and flush it first, before updating the

		 * pte with the new entry. This will avoid a race condition
@@ -2592,7 +2592,7 @@ static int wp_page_copy(struct vm_fault *vmf) 
		 * Don't let another task, with possibly unlocked vma,

		 * keep the mlocked page.

		 */

		if (page_copied && (vma->vm_flags & VM_LOCKED)) {

		if (page_copied && (vmf->vma_flags & VM_LOCKED)) {

			lock_page(old_page);	/* LRU manipulation */

			if (PageMlocked(old_page))

				munlock_vma_page(old_page);
@@ -2628,7 +2628,7 @@ static int wp_page_copy(struct vm_fault *vmf) 
 */

int finish_mkwrite_fault(struct vm_fault *vmf)

{

	WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));

	WARN_ON_ONCE(!(vmf->vma_flags & VM_SHARED));

	if (!pte_map_lock(vmf))

		return VM_FAULT_RETRY;

	/*
@@ -2730,7 +2730,7 @@ static int do_wp_page(struct vm_fault *vmf) 
		 * We should not cow pages in a shared writeable mapping.

		 * Just mark the pages writable and/or call ops->pfn_mkwrite.

		 */

		if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==

		if ((vmf->vma_flags & (VM_WRITE|VM_SHARED)) ==

				     (VM_WRITE|VM_SHARED))

			return wp_pfn_shared(vmf);
@@ -2777,7 +2777,7 @@ static int do_wp_page(struct vm_fault *vmf) 
			return VM_FAULT_WRITE;

		}

		unlock_page(vmf->page);

	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==

	} else if (unlikely((vmf->vma_flags & (VM_WRITE|VM_SHARED)) ==

					(VM_WRITE|VM_SHARED))) {

		return wp_page_shared(vmf);

	}
@@ -3038,9 +3038,9 @@ int do_swap_page(struct vm_fault *vmf) 


	inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);

	dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);

	pte = mk_pte(page, vma->vm_page_prot);

	pte = mk_pte(page, vmf->vma_page_prot);

	if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {

		pte = maybe_mkwrite(pte_mkdirty(pte), vma);

		pte = maybe_mkwrite(pte_mkdirty(pte), vmf->vma_flags);

		vmf->flags &= ~FAULT_FLAG_WRITE;

		ret |= VM_FAULT_WRITE;

		exclusive = RMAP_EXCLUSIVE;
@@ -3064,7 +3064,7 @@ int do_swap_page(struct vm_fault *vmf) 


	swap_free(entry);

	if (mem_cgroup_swap_full(page) ||

	    (vma->vm_flags & VM_LOCKED) || PageMlocked(page))

	    (vmf->vma_flags & VM_LOCKED) || PageMlocked(page))

		try_to_free_swap(page);

	unlock_page(page);

	if (page != swapcache && swapcache) {
@@ -3122,7 +3122,7 @@ static int do_anonymous_page(struct vm_fault *vmf) 
	pte_t entry;



	/* File mapping without ->vm_ops ? */

	if (vma->vm_flags & VM_SHARED)

	if (vmf->vma_flags & VM_SHARED)

		return VM_FAULT_SIGBUS;



	/*
@@ -3146,7 +3146,7 @@ static int do_anonymous_page(struct vm_fault *vmf) 
	if (!(vmf->flags & FAULT_FLAG_WRITE) &&

			!mm_forbids_zeropage(vma->vm_mm)) {

		entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),

						vma->vm_page_prot));

						vmf->vma_page_prot));

		if (!pte_map_lock(vmf))

			return VM_FAULT_RETRY;

		if (!pte_none(*vmf->pte))
@@ -3179,8 +3179,8 @@ static int do_anonymous_page(struct vm_fault *vmf) 
	 */

	__SetPageUptodate(page);



	entry = mk_pte(page, vma->vm_page_prot);

	if (vma->vm_flags & VM_WRITE)

	entry = mk_pte(page, vmf->vma_page_prot);

	if (vmf->vma_flags & VM_WRITE)

		entry = pte_mkwrite(pte_mkdirty(entry));



	if (!pte_map_lock(vmf)) {
@@ -3377,7 +3377,7 @@ static int do_set_pmd(struct vm_fault *vmf, struct page *page) 
	for (i = 0; i < HPAGE_PMD_NR; i++)

		flush_icache_page(vma, page + i);



	entry = mk_huge_pmd(page, vma->vm_page_prot);

	entry = mk_huge_pmd(page, vmf->vma_page_prot);

	if (write)

		entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
@@ -3451,11 +3451,11 @@ int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg, 
		return VM_FAULT_NOPAGE;



	flush_icache_page(vma, page);

	entry = mk_pte(page, vma->vm_page_prot);

	entry = mk_pte(page, vmf->vma_page_prot);

	if (write)

		entry = maybe_mkwrite(pte_mkdirty(entry), vma);

		entry = maybe_mkwrite(pte_mkdirty(entry), vmf->vma_flags);

	/* copy-on-write page */

	if (write && !(vma->vm_flags & VM_SHARED)) {

	if (write && !(vmf->vma_flags & VM_SHARED)) {

		inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);

		page_add_new_anon_rmap(page, vma, vmf->address, false);

		mem_cgroup_commit_charge(page, memcg, false, false);
@@ -3494,7 +3494,7 @@ int finish_fault(struct vm_fault *vmf) 


	/* Did we COW the page? */

	if ((vmf->flags & FAULT_FLAG_WRITE) &&

	    !(vmf->vma->vm_flags & VM_SHARED))

	    !(vmf->vma_flags & VM_SHARED))

		page = vmf->cow_page;

	else

		page = vmf->page;
@@ -3748,7 +3748,7 @@ static int do_fault(struct vm_fault *vmf) 
		ret = VM_FAULT_SIGBUS;

	else if (!(vmf->flags & FAULT_FLAG_WRITE))

		ret = do_read_fault(vmf);

	else if (!(vma->vm_flags & VM_SHARED))

	else if (!(vmf->vma_flags & VM_SHARED))

		ret = do_cow_fault(vmf);

	else

		ret = do_shared_fault(vmf);
@@ -3805,7 +3805,7 @@ static int do_numa_page(struct vm_fault *vmf) 
	 * accessible ptes, some can allow access by kernel mode.

	 */

	pte = ptep_modify_prot_start(vma->vm_mm, vmf->address, vmf->pte);

	pte = pte_modify(pte, vma->vm_page_prot);

	pte = pte_modify(pte, vmf->vma_page_prot);

	pte = pte_mkyoung(pte);

	if (was_writable)

		pte = pte_mkwrite(pte);
@@ -3839,7 +3839,7 @@ static int do_numa_page(struct vm_fault *vmf) 
	 * Flag if the page is shared between multiple address spaces. This

	 * is later used when determining whether to group tasks together

	 */

	if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))

	if (page_mapcount(page) > 1 && (vmf->vma_flags & VM_SHARED))

		flags |= TNF_SHARED;



	last_cpupid = page_cpupid_last(page);
@@ -3883,7 +3883,7 @@ static int wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd) 
		return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);



	/* COW handled on pte level: split pmd */

	VM_BUG_ON_VMA(vmf->vma->vm_flags & VM_SHARED, vmf->vma);

	VM_BUG_ON_VMA(vmf->vma_flags & VM_SHARED, vmf->vma);

	__split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);



	return VM_FAULT_FALLBACK;
@@ -4030,6 +4030,8 @@ static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address, 
		.flags = flags,

		.pgoff = linear_page_index(vma, address),

		.gfp_mask = __get_fault_gfp_mask(vma),

		.vma_flags = vma->vm_flags,

		.vma_page_prot = vma->vm_page_prot,

	};

	unsigned int dirty = flags & FAULT_FLAG_WRITE;

	struct mm_struct *mm = vma->vm_mm;