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-rw-r--r--mm/memory.c149
1 files changed, 127 insertions, 22 deletions
diff --git a/mm/memory.c b/mm/memory.c
index e9bce27bc18c..b001670c9615 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -117,6 +117,18 @@ int randomize_va_space __read_mostly =
2;
#endif
+#ifndef arch_faults_on_old_pte
+static inline bool arch_faults_on_old_pte(void)
+{
+ /*
+ * Those arches which don't have hw access flag feature need to
+ * implement their own helper. By default, "true" means pagefault
+ * will be hit on old pte.
+ */
+ return true;
+}
+#endif
+
static int __init disable_randmaps(char *s)
{
randomize_va_space = 0;
@@ -137,7 +149,7 @@ static int __init init_zero_pfn(void)
zero_pfn = page_to_pfn(ZERO_PAGE(0));
return 0;
}
-core_initcall(init_zero_pfn);
+early_initcall(init_zero_pfn);
#if defined(SPLIT_RSS_COUNTING)
@@ -323,6 +335,16 @@ bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_
return false;
}
+void tlb_flush_pmd_range(struct mmu_gather *tlb, unsigned long address,
+ unsigned long size)
+{
+ if (tlb->page_size != 0 && tlb->page_size != PMD_SIZE)
+ tlb_flush_mmu(tlb);
+
+ tlb->page_size = PMD_SIZE;
+ tlb->start = min(tlb->start, address);
+ tlb->end = max(tlb->end, address + size);
+}
#endif /* HAVE_GENERIC_MMU_GATHER */
#ifdef CONFIG_HAVE_RCU_TABLE_FREE
@@ -1972,11 +1994,11 @@ static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
unsigned long addr, unsigned long end,
unsigned long pfn, pgprot_t prot)
{
- pte_t *pte;
+ pte_t *pte, *mapped_pte;
spinlock_t *ptl;
int err = 0;
- pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
+ mapped_pte = pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
if (!pte)
return -ENOMEM;
arch_enter_lazy_mmu_mode();
@@ -1990,7 +2012,7 @@ static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
pfn++;
} while (pte++, addr += PAGE_SIZE, addr != end);
arch_leave_lazy_mmu_mode();
- pte_unmap_unlock(pte - 1, ptl);
+ pte_unmap_unlock(mapped_pte, ptl);
return err;
}
@@ -2324,32 +2346,101 @@ static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
return same;
}
-static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
+static inline bool cow_user_page(struct page *dst, struct page *src,
+ struct vm_fault *vmf)
{
+ bool ret;
+ void *kaddr;
+ void __user *uaddr;
+ bool locked = false;
+ struct vm_area_struct *vma = vmf->vma;
+ struct mm_struct *mm = vma->vm_mm;
+ unsigned long addr = vmf->address;
+
debug_dma_assert_idle(src);
+ if (likely(src)) {
+ copy_user_highpage(dst, src, addr, vma);
+ return true;
+ }
+
/*
* If the source page was a PFN mapping, we don't have
* a "struct page" for it. We do a best-effort copy by
* just copying from the original user address. If that
* fails, we just zero-fill it. Live with it.
*/
- if (unlikely(!src)) {
- void *kaddr = kmap_atomic(dst);
- void __user *uaddr = (void __user *)(va & PAGE_MASK);
+ kaddr = kmap_atomic(dst);
+ uaddr = (void __user *)(addr & PAGE_MASK);
+
+ /*
+ * On architectures with software "accessed" bits, we would
+ * take a double page fault, so mark it accessed here.
+ */
+ if (arch_faults_on_old_pte() && !pte_young(vmf->orig_pte)) {
+ pte_t entry;
+
+ vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
+ locked = true;
+ if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) {
+ /*
+ * Other thread has already handled the fault
+ * and we don't need to do anything. If it's
+ * not the case, the fault will be triggered
+ * again on the same address.
+ */
+ ret = false;
+ goto pte_unlock;
+ }
+
+ entry = pte_mkyoung(vmf->orig_pte);
+ if (ptep_set_access_flags(vma, addr, vmf->pte, entry, 0))
+ update_mmu_cache(vma, addr, vmf->pte);
+ }
+
+ /*
+ * This really shouldn't fail, because the page is there
+ * in the page tables. But it might just be unreadable,
+ * in which case we just give up and fill the result with
+ * zeroes.
+ */
+ if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
+ if (locked)
+ goto warn;
+
+ /* Re-validate under PTL if the page is still mapped */
+ vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
+ locked = true;
+ if (!likely(pte_same(*vmf->pte, vmf->orig_pte))) {
+ /* The PTE changed under us. Retry page fault. */
+ ret = false;
+ goto pte_unlock;
+ }
/*
- * This really shouldn't fail, because the page is there
- * in the page tables. But it might just be unreadable,
- * in which case we just give up and fill the result with
- * zeroes.
+ * The same page can be mapped back since last copy attampt.
+ * Try to copy again under PTL.
*/
- if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
+ if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
+ /*
+ * Give a warn in case there can be some obscure
+ * use-case
+ */
+warn:
+ WARN_ON_ONCE(1);
clear_page(kaddr);
- kunmap_atomic(kaddr);
- flush_dcache_page(dst);
- } else
- copy_user_highpage(dst, src, va, vma);
+ }
+ }
+
+ ret = true;
+
+pte_unlock:
+ if (locked)
+ pte_unmap_unlock(vmf->pte, vmf->ptl);
+ kunmap_atomic(kaddr);
+ flush_dcache_page(dst);
+
+ return ret;
}
static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
@@ -2503,7 +2594,19 @@ static int wp_page_copy(struct vm_fault *vmf)
vmf->address);
if (!new_page)
goto oom;
- cow_user_page(new_page, old_page, vmf->address, vma);
+
+ if (!cow_user_page(new_page, old_page, vmf)) {
+ /*
+ * COW failed, if the fault was solved by other,
+ * it's fine. If not, userspace would re-fault on
+ * the same address and we will handle the fault
+ * from the second attempt.
+ */
+ put_page(new_page);
+ if (old_page)
+ put_page(old_page);
+ return 0;
+ }
}
if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false))
@@ -4700,17 +4803,19 @@ long copy_huge_page_from_user(struct page *dst_page,
void *page_kaddr;
unsigned long i, rc = 0;
unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
+ struct page *subpage = dst_page;
- for (i = 0; i < pages_per_huge_page; i++) {
+ for (i = 0; i < pages_per_huge_page;
+ i++, subpage = mem_map_next(subpage, dst_page, i)) {
if (allow_pagefault)
- page_kaddr = kmap(dst_page + i);
+ page_kaddr = kmap(subpage);
else
- page_kaddr = kmap_atomic(dst_page + i);
+ page_kaddr = kmap_atomic(subpage);
rc = copy_from_user(page_kaddr,
(const void __user *)(src + i * PAGE_SIZE),
PAGE_SIZE);
if (allow_pagefault)
- kunmap(dst_page + i);
+ kunmap(subpage);
else
kunmap_atomic(page_kaddr);
generated by cgit 1.2.3-korg (git 2.39.0) at 2024-04-30 19:50:28 +0000