From 54ef3ae0d821229ecfc3ba1205fa620ee8db3d5c Mon Sep 17 00:00:00 2001 From: Haggai Eran Date: Fri, 28 Sep 2012 10:19:57 +1000 Subject: [PATCH] mm: wrap calls to set_pte_at_notify with invalidate_range_start and invalidate_range_end In order to allow sleeping during invalidate_page mmu notifier calls, we need to avoid calling when holding the PT lock. In addition to its direct calls, invalidate_page can also be called as a substitute for a change_pte call, in case the notifier client hasn't implemented change_pte. This patch drops the invalidate_page call from change_pte, and instead wraps all calls to change_pte with invalidate_range_start and invalidate_range_end calls. Note that change_pte still cannot sleep after this patch, and that clients implementing change_pte should not take action on it in case the number of outstanding invalidate_range_start calls is larger than one, otherwise they might miss a later invalidation. Signed-off-by: Haggai Eran Cc: Andrea Arcangeli Cc: Sagi Grimberg Cc: Peter Zijlstra Cc: Xiao Guangrong Cc: Or Gerlitz Cc: Haggai Eran Cc: Shachar Raindel Cc: Liran Liss Cc: Christoph Lameter Cc: Avi Kivity Cc: Hugh Dickins Signed-off-by: Andrew Morton --- kernel/events/uprobes.c | 5 +++++ mm/ksm.c | 21 +++++++++++++++++++-- mm/memory.c | 17 +++++++++++------ mm/mmu_notifier.c | 6 ------ 4 files changed, 35 insertions(+), 14 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 1d9c0a985960..98256bc71ee1 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -141,10 +141,14 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, spinlock_t *ptl; pte_t *ptep; int err; + /* For mmu_notifiers */ + const unsigned long mmun_start = addr; + const unsigned long mmun_end = addr + PAGE_SIZE; /* For try_to_free_swap() and munlock_vma_page() below */ lock_page(page); + mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); err = -EAGAIN; ptep = page_check_address(page, mm, addr, &ptl, 0); if (!ptep) @@ -173,6 +177,7 @@ static int __replace_page(struct vm_area_struct *vma, unsigned long addr, err = 0; unlock: + mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); unlock_page(page); return err; } diff --git a/mm/ksm.c b/mm/ksm.c index ecbc090cdaad..ae539f0b8aa1 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -709,15 +709,22 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page, spinlock_t *ptl; int swapped; int err = -EFAULT; + unsigned long mmun_start; /* For mmu_notifiers */ + unsigned long mmun_end; /* For mmu_notifiers */ addr = page_address_in_vma(page, vma); if (addr == -EFAULT) goto out; BUG_ON(PageTransCompound(page)); + + mmun_start = addr; + mmun_end = addr + PAGE_SIZE; + mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); + ptep = page_check_address(page, mm, addr, &ptl, 0); if (!ptep) - goto out; + goto out_mn; if (pte_write(*ptep) || pte_dirty(*ptep)) { pte_t entry; @@ -752,6 +759,8 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page, out_unlock: pte_unmap_unlock(ptep, ptl); +out_mn: + mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); out: return err; } @@ -776,6 +785,8 @@ static int replace_page(struct vm_area_struct *vma, struct page *page, spinlock_t *ptl; unsigned long addr; int err = -EFAULT; + unsigned long mmun_start; /* For mmu_notifiers */ + unsigned long mmun_end; /* For mmu_notifiers */ addr = page_address_in_vma(page, vma); if (addr == -EFAULT) @@ -794,10 +805,14 @@ static int replace_page(struct vm_area_struct *vma, struct page *page, if (!pmd_present(*pmd)) goto out; + mmun_start = addr; + mmun_end = addr + PAGE_SIZE; + mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); + ptep = pte_offset_map_lock(mm, pmd, addr, &ptl); if (!pte_same(*ptep, orig_pte)) { pte_unmap_unlock(ptep, ptl); - goto out; + goto out_mn; } get_page(kpage); @@ -814,6 +829,8 @@ static int replace_page(struct vm_area_struct *vma, struct page *page, pte_unmap_unlock(ptep, ptl); err = 0; +out_mn: + mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); out: return err; } diff --git a/mm/memory.c b/mm/memory.c index 4c1a3f21199a..7d5238884dff 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2532,6 +2532,8 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, int ret = 0; int page_mkwrite = 0; struct page *dirty_page = NULL; + unsigned long mmun_start; /* For mmu_notifiers */ + unsigned long mmun_end; /* For mmu_notifiers */ old_page = vm_normal_page(vma, address, orig_pte); if (!old_page) { @@ -2709,6 +2711,10 @@ gotten: if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL)) goto oom_free_new; + mmun_start = address & PAGE_MASK; + mmun_end = (address & PAGE_MASK) + PAGE_SIZE; + mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); + /* * Re-check the pte - we dropped the lock */ @@ -2771,14 +2777,13 @@ gotten: } else mem_cgroup_uncharge_page(new_page); + if (new_page) + page_cache_release(new_page); unlock: pte_unmap_unlock(page_table, ptl); - if (new_page) { - if (new_page == old_page) - /* cow happened, notify before releasing old_page */ - mmu_notifier_invalidate_page(mm, address); - page_cache_release(new_page); - } + if (new_page) + /* Only call the end notifier if the begin was called. */ + mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); if (old_page) { /* * Don't let another task, with possibly unlocked vma, diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c index c297142f0fe6..479a1e751a73 100644 --- a/mm/mmu_notifier.c +++ b/mm/mmu_notifier.c @@ -137,12 +137,6 @@ void __mmu_notifier_change_pte(struct mm_struct *mm, unsigned long address, hlist_for_each_entry_rcu(mn, n, &mm->mmu_notifier_mm->list, hlist) { if (mn->ops->change_pte) mn->ops->change_pte(mn, mm, address, pte); - /* - * Some drivers don't have change_pte, - * so we must call invalidate_page in that case. - */ - else if (mn->ops->invalidate_page) - mn->ops->invalidate_page(mn, mm, address); } srcu_read_unlock(&srcu, id); } -- 2.39.2