--- /dev/null
+From 575bc2a7dde881a6409e1c5952b6692b33a22446 Mon Sep 17 00:00:00 2001
+From: Hugh Dickins <hughd@google.com>
+Date: Fri, 30 Nov 2018 14:10:21 -0800
+Subject: mm/huge_memory: fix lockdep complaint on 32-bit i_size_read()
+
+commit 006d3ff27e884f80bd7d306b041afc415f63598f upstream.
+
+Huge tmpfs testing, on 32-bit kernel with lockdep enabled, showed that
+__split_huge_page() was using i_size_read() while holding the irq-safe
+lru_lock and page tree lock, but the 32-bit i_size_read() uses an
+irq-unsafe seqlock which should not be nested inside them.
+
+Instead, read the i_size earlier in split_huge_page_to_list(), and pass
+the end offset down to __split_huge_page(): all while holding head page
+lock, which is enough to prevent truncation of that extent before the
+page tree lock has been taken.
+
+Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261520070.2275@eggly.anvils
+Fixes: baa355fd33142 ("thp: file pages support for split_huge_page()")
+Signed-off-by: Hugh Dickins <hughd@google.com>
+Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
+Cc: Jerome Glisse <jglisse@redhat.com>
+Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Cc: Matthew Wilcox <willy@infradead.org>
+Cc: <stable@vger.kernel.org> [4.8+]
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ mm/huge_memory.c | 19 +++++++++++++------
+ 1 file changed, 13 insertions(+), 6 deletions(-)
+
+diff --git a/mm/huge_memory.c b/mm/huge_memory.c
+index 69ffeb439b0f..930f2aa3bb4d 100644
+--- a/mm/huge_memory.c
++++ b/mm/huge_memory.c
+@@ -2362,12 +2362,11 @@ static void __split_huge_page_tail(struct page *head, int tail,
+ }
+
+ static void __split_huge_page(struct page *page, struct list_head *list,
+- unsigned long flags)
++ pgoff_t end, unsigned long flags)
+ {
+ struct page *head = compound_head(page);
+ struct zone *zone = page_zone(head);
+ struct lruvec *lruvec;
+- pgoff_t end = -1;
+ int i;
+
+ lruvec = mem_cgroup_page_lruvec(head, zone->zone_pgdat);
+@@ -2375,9 +2374,6 @@ static void __split_huge_page(struct page *page, struct list_head *list,
+ /* complete memcg works before add pages to LRU */
+ mem_cgroup_split_huge_fixup(head);
+
+- if (!PageAnon(page))
+- end = DIV_ROUND_UP(i_size_read(head->mapping->host), PAGE_SIZE);
+-
+ for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
+ __split_huge_page_tail(head, i, lruvec, list);
+ /* Some pages can be beyond i_size: drop them from page cache */
+@@ -2549,6 +2545,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
+ int count, mapcount, extra_pins, ret;
+ bool mlocked;
+ unsigned long flags;
++ pgoff_t end;
+
+ VM_BUG_ON_PAGE(is_huge_zero_page(page), page);
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
+@@ -2571,6 +2568,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
+ ret = -EBUSY;
+ goto out;
+ }
++ end = -1;
+ mapping = NULL;
+ anon_vma_lock_write(anon_vma);
+ } else {
+@@ -2584,6 +2582,15 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
+
+ anon_vma = NULL;
+ i_mmap_lock_read(mapping);
++
++ /*
++ *__split_huge_page() may need to trim off pages beyond EOF:
++ * but on 32-bit, i_size_read() takes an irq-unsafe seqlock,
++ * which cannot be nested inside the page tree lock. So note
++ * end now: i_size itself may be changed at any moment, but
++ * head page lock is good enough to serialize the trimming.
++ */
++ end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
+ }
+
+ /*
+@@ -2633,7 +2640,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
+ if (mapping)
+ __dec_node_page_state(page, NR_SHMEM_THPS);
+ spin_unlock(&pgdata->split_queue_lock);
+- __split_huge_page(page, list, flags);
++ __split_huge_page(page, list, end, flags);
+ if (PageSwapCache(head)) {
+ swp_entry_t entry = { .val = page_private(head) };
+
+--
+2.17.1
+
--- /dev/null
+From 4b7dfccb19a765221895965850eacd4f12621e36 Mon Sep 17 00:00:00 2001
+From: Hugh Dickins <hughd@google.com>
+Date: Fri, 30 Nov 2018 14:10:13 -0800
+Subject: mm/huge_memory: rename freeze_page() to unmap_page()
+
+commit 906f9cdfc2a0800f13683f9e4ebdfd08c12ee81b upstream.
+
+The term "freeze" is used in several ways in the kernel, and in mm it
+has the particular meaning of forcing page refcount temporarily to 0.
+freeze_page() is just too confusing a name for a function that unmaps a
+page: rename it unmap_page(), and rename unfreeze_page() remap_page().
+
+Went to change the mention of freeze_page() added later in mm/rmap.c,
+but found it to be incorrect: ordinary page reclaim reaches there too;
+but the substance of the comment still seems correct, so edit it down.
+
+Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261514080.2275@eggly.anvils
+Fixes: e9b61f19858a5 ("thp: reintroduce split_huge_page()")
+Signed-off-by: Hugh Dickins <hughd@google.com>
+Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
+Cc: Jerome Glisse <jglisse@redhat.com>
+Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Cc: Matthew Wilcox <willy@infradead.org>
+Cc: <stable@vger.kernel.org> [4.8+]
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ mm/huge_memory.c | 12 ++++++------
+ 1 file changed, 6 insertions(+), 6 deletions(-)
+
+diff --git a/mm/huge_memory.c b/mm/huge_memory.c
+index adacfe66cf3d..09d7e9c4de89 100644
+--- a/mm/huge_memory.c
++++ b/mm/huge_memory.c
+@@ -2280,7 +2280,7 @@ void vma_adjust_trans_huge(struct vm_area_struct *vma,
+ }
+ }
+
+-static void freeze_page(struct page *page)
++static void unmap_page(struct page *page)
+ {
+ enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
+ TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;
+@@ -2295,7 +2295,7 @@ static void freeze_page(struct page *page)
+ VM_BUG_ON_PAGE(!unmap_success, page);
+ }
+
+-static void unfreeze_page(struct page *page)
++static void remap_page(struct page *page)
+ {
+ int i;
+ if (PageTransHuge(page)) {
+@@ -2412,7 +2412,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
+
+ spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
+
+- unfreeze_page(head);
++ remap_page(head);
+
+ for (i = 0; i < HPAGE_PMD_NR; i++) {
+ struct page *subpage = head + i;
+@@ -2593,7 +2593,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
+ }
+
+ /*
+- * Racy check if we can split the page, before freeze_page() will
++ * Racy check if we can split the page, before unmap_page() will
+ * split PMDs
+ */
+ if (!can_split_huge_page(head, &extra_pins)) {
+@@ -2602,7 +2602,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
+ }
+
+ mlocked = PageMlocked(page);
+- freeze_page(head);
++ unmap_page(head);
+ VM_BUG_ON_PAGE(compound_mapcount(head), head);
+
+ /* Make sure the page is not on per-CPU pagevec as it takes pin */
+@@ -2659,7 +2659,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
+ fail: if (mapping)
+ spin_unlock(&mapping->tree_lock);
+ spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
+- unfreeze_page(head);
++ remap_page(head);
+ ret = -EBUSY;
+ }
+
+--
+2.17.1
+
--- /dev/null
+From c7f21aed153c0324a97a1eebdd4019b1a588355a Mon Sep 17 00:00:00 2001
+From: Hugh Dickins <hughd@google.com>
+Date: Fri, 30 Nov 2018 14:10:16 -0800
+Subject: mm/huge_memory: splitting set mapping+index before unfreeze
+
+commit 173d9d9fd3ddae84c110fea8aedf1f26af6be9ec upstream.
+
+Huge tmpfs stress testing has occasionally hit shmem_undo_range()'s
+VM_BUG_ON_PAGE(page_to_pgoff(page) != index, page).
+
+Move the setting of mapping and index up before the page_ref_unfreeze()
+in __split_huge_page_tail() to fix this: so that a page cache lookup
+cannot get a reference while the tail's mapping and index are unstable.
+
+In fact, might as well move them up before the smp_wmb(): I don't see an
+actual need for that, but if I'm missing something, this way round is
+safer than the other, and no less efficient.
+
+You might argue that VM_BUG_ON_PAGE(page_to_pgoff(page) != index, page) is
+misplaced, and should be left until after the trylock_page(); but left as
+is has not crashed since, and gives more stringent assurance.
+
+Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261516380.2275@eggly.anvils
+Fixes: e9b61f19858a5 ("thp: reintroduce split_huge_page()")
+Requires: 605ca5ede764 ("mm/huge_memory.c: reorder operations in __split_huge_page_tail()")
+Signed-off-by: Hugh Dickins <hughd@google.com>
+Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
+Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Cc: Jerome Glisse <jglisse@redhat.com>
+Cc: Matthew Wilcox <willy@infradead.org>
+Cc: <stable@vger.kernel.org> [4.8+]
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ mm/huge_memory.c | 12 ++++++------
+ 1 file changed, 6 insertions(+), 6 deletions(-)
+
+diff --git a/mm/huge_memory.c b/mm/huge_memory.c
+index 8969f5cf3174..69ffeb439b0f 100644
+--- a/mm/huge_memory.c
++++ b/mm/huge_memory.c
+@@ -2331,6 +2331,12 @@ static void __split_huge_page_tail(struct page *head, int tail,
+ (1L << PG_unevictable) |
+ (1L << PG_dirty)));
+
++ /* ->mapping in first tail page is compound_mapcount */
++ VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
++ page_tail);
++ page_tail->mapping = head->mapping;
++ page_tail->index = head->index + tail;
++
+ /* Page flags must be visible before we make the page non-compound. */
+ smp_wmb();
+
+@@ -2351,12 +2357,6 @@ static void __split_huge_page_tail(struct page *head, int tail,
+ if (page_is_idle(head))
+ set_page_idle(page_tail);
+
+- /* ->mapping in first tail page is compound_mapcount */
+- VM_BUG_ON_PAGE(tail > 2 && page_tail->mapping != TAIL_MAPPING,
+- page_tail);
+- page_tail->mapping = head->mapping;
+-
+- page_tail->index = head->index + tail;
+ page_cpupid_xchg_last(page_tail, page_cpupid_last(head));
+ lru_add_page_tail(head, page_tail, lruvec, list);
+ }
+--
+2.17.1
+
--- /dev/null
+From ea057a6ec630ca0abb5485ecd1336eb92e4a4d92 Mon Sep 17 00:00:00 2001
+From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Date: Thu, 5 Apr 2018 16:23:28 -0700
+Subject: mm/huge_memory.c: reorder operations in __split_huge_page_tail()
+
+commit 605ca5ede7643a01f4c4a15913f9714ac297f8a6 upstream.
+
+THP split makes non-atomic change of tail page flags. This is almost ok
+because tail pages are locked and isolated but this breaks recent
+changes in page locking: non-atomic operation could clear bit
+PG_waiters.
+
+As a result concurrent sequence get_page_unless_zero() -> lock_page()
+might block forever. Especially if this page was truncated later.
+
+Fix is trivial: clone flags before unfreezing page reference counter.
+
+This race exists since commit 62906027091f ("mm: add PageWaiters
+indicating tasks are waiting for a page bit") while unsave unfreeze
+itself was added in commit 8df651c7059e ("thp: cleanup
+split_huge_page()").
+
+clear_compound_head() also must be called before unfreezing page
+reference because after successful get_page_unless_zero() might follow
+put_page() which needs correct compound_head().
+
+And replace page_ref_inc()/page_ref_add() with page_ref_unfreeze() which
+is made especially for that and has semantic of smp_store_release().
+
+Link: http://lkml.kernel.org/r/151844393341.210639.13162088407980624477.stgit@buzz
+Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
+Cc: Michal Hocko <mhocko@suse.com>
+Cc: Nicholas Piggin <npiggin@gmail.com>
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ mm/huge_memory.c | 36 +++++++++++++++---------------------
+ 1 file changed, 15 insertions(+), 21 deletions(-)
+
+diff --git a/mm/huge_memory.c b/mm/huge_memory.c
+index 09d7e9c4de89..8969f5cf3174 100644
+--- a/mm/huge_memory.c
++++ b/mm/huge_memory.c
+@@ -2312,26 +2312,13 @@ static void __split_huge_page_tail(struct page *head, int tail,
+ struct page *page_tail = head + tail;
+
+ VM_BUG_ON_PAGE(atomic_read(&page_tail->_mapcount) != -1, page_tail);
+- VM_BUG_ON_PAGE(page_ref_count(page_tail) != 0, page_tail);
+
+ /*
+- * tail_page->_refcount is zero and not changing from under us. But
+- * get_page_unless_zero() may be running from under us on the
+- * tail_page. If we used atomic_set() below instead of atomic_inc() or
+- * atomic_add(), we would then run atomic_set() concurrently with
+- * get_page_unless_zero(), and atomic_set() is implemented in C not
+- * using locked ops. spin_unlock on x86 sometime uses locked ops
+- * because of PPro errata 66, 92, so unless somebody can guarantee
+- * atomic_set() here would be safe on all archs (and not only on x86),
+- * it's safer to use atomic_inc()/atomic_add().
++ * Clone page flags before unfreezing refcount.
++ *
++ * After successful get_page_unless_zero() might follow flags change,
++ * for exmaple lock_page() which set PG_waiters.
+ */
+- if (PageAnon(head) && !PageSwapCache(head)) {
+- page_ref_inc(page_tail);
+- } else {
+- /* Additional pin to radix tree */
+- page_ref_add(page_tail, 2);
+- }
+-
+ page_tail->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+ page_tail->flags |= (head->flags &
+ ((1L << PG_referenced) |
+@@ -2344,14 +2331,21 @@ static void __split_huge_page_tail(struct page *head, int tail,
+ (1L << PG_unevictable) |
+ (1L << PG_dirty)));
+
+- /*
+- * After clearing PageTail the gup refcount can be released.
+- * Page flags also must be visible before we make the page non-compound.
+- */
++ /* Page flags must be visible before we make the page non-compound. */
+ smp_wmb();
+
++ /*
++ * Clear PageTail before unfreezing page refcount.
++ *
++ * After successful get_page_unless_zero() might follow put_page()
++ * which needs correct compound_head().
++ */
+ clear_compound_head(page_tail);
+
++ /* Finally unfreeze refcount. Additional reference from page cache. */
++ page_ref_unfreeze(page_tail, 1 + (!PageAnon(head) ||
++ PageSwapCache(head)));
++
+ if (page_is_young(head))
+ set_page_young(page_tail);
+ if (page_is_idle(head))
+--
+2.17.1
+
--- /dev/null
+From 71185a50fb2cd332bcfeb6b847c78c10244f0f23 Mon Sep 17 00:00:00 2001
+From: Hugh Dickins <hughd@google.com>
+Date: Fri, 30 Nov 2018 14:10:47 -0800
+Subject: mm/khugepaged: collapse_shmem() do not crash on Compound
+
+commit 06a5e1268a5fb9c2b346a3da6b97e85f2eba0f07 upstream.
+
+collapse_shmem()'s VM_BUG_ON_PAGE(PageTransCompound) was unsafe: before
+it holds page lock of the first page, racing truncation then extension
+might conceivably have inserted a hugepage there already. Fail with the
+SCAN_PAGE_COMPOUND result, instead of crashing (CONFIG_DEBUG_VM=y) or
+otherwise mishandling the unexpected hugepage - though later we might
+code up a more constructive way of handling it, with SCAN_SUCCESS.
+
+Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261529310.2275@eggly.anvils
+Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages")
+Signed-off-by: Hugh Dickins <hughd@google.com>
+Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
+Cc: Jerome Glisse <jglisse@redhat.com>
+Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Cc: Matthew Wilcox <willy@infradead.org>
+Cc: <stable@vger.kernel.org> [4.8+]
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ mm/khugepaged.c | 10 +++++++++-
+ 1 file changed, 9 insertions(+), 1 deletion(-)
+
+diff --git a/mm/khugepaged.c b/mm/khugepaged.c
+index 45bf0e5775f7..d27a73737f1a 100644
+--- a/mm/khugepaged.c
++++ b/mm/khugepaged.c
+@@ -1401,7 +1401,15 @@ static void collapse_shmem(struct mm_struct *mm,
+ */
+ VM_BUG_ON_PAGE(!PageLocked(page), page);
+ VM_BUG_ON_PAGE(!PageUptodate(page), page);
+- VM_BUG_ON_PAGE(PageTransCompound(page), page);
++
++ /*
++ * If file was truncated then extended, or hole-punched, before
++ * we locked the first page, then a THP might be there already.
++ */
++ if (PageTransCompound(page)) {
++ result = SCAN_PAGE_COMPOUND;
++ goto out_unlock;
++ }
+
+ if (page_mapping(page) != mapping) {
+ result = SCAN_TRUNCATED;
+--
+2.17.1
+
--- /dev/null
+From 4d5505b968a7e8e5d14db46b3aa14448f6eecca4 Mon Sep 17 00:00:00 2001
+From: Hugh Dickins <hughd@google.com>
+Date: Fri, 30 Nov 2018 14:10:35 -0800
+Subject: mm/khugepaged: collapse_shmem() remember to clear holes
+
+commit 2af8ff291848cc4b1cce24b6c943394eb2c761e8 upstream.
+
+Huge tmpfs testing reminds us that there is no __GFP_ZERO in the gfp
+flags khugepaged uses to allocate a huge page - in all common cases it
+would just be a waste of effort - so collapse_shmem() must remember to
+clear out any holes that it instantiates.
+
+The obvious place to do so, where they are put into the page cache tree,
+is not a good choice: because interrupts are disabled there. Leave it
+until further down, once success is assured, where the other pages are
+copied (before setting PageUptodate).
+
+Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261525080.2275@eggly.anvils
+Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages")
+Signed-off-by: Hugh Dickins <hughd@google.com>
+Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
+Cc: Jerome Glisse <jglisse@redhat.com>
+Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Cc: Matthew Wilcox <willy@infradead.org>
+Cc: <stable@vger.kernel.org> [4.8+]
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ mm/khugepaged.c | 10 ++++++++++
+ 1 file changed, 10 insertions(+)
+
+diff --git a/mm/khugepaged.c b/mm/khugepaged.c
+index be7b0863e33c..f535dbe3f9f5 100644
+--- a/mm/khugepaged.c
++++ b/mm/khugepaged.c
+@@ -1502,7 +1502,12 @@ static void collapse_shmem(struct mm_struct *mm,
+ * Replacing old pages with new one has succeed, now we need to
+ * copy the content and free old pages.
+ */
++ index = start;
+ list_for_each_entry_safe(page, tmp, &pagelist, lru) {
++ while (index < page->index) {
++ clear_highpage(new_page + (index % HPAGE_PMD_NR));
++ index++;
++ }
+ copy_highpage(new_page + (page->index % HPAGE_PMD_NR),
+ page);
+ list_del(&page->lru);
+@@ -1512,6 +1517,11 @@ static void collapse_shmem(struct mm_struct *mm,
+ ClearPageActive(page);
+ ClearPageUnevictable(page);
+ put_page(page);
++ index++;
++ }
++ while (index < end) {
++ clear_highpage(new_page + (index % HPAGE_PMD_NR));
++ index++;
+ }
+
+ local_irq_save(flags);
+--
+2.17.1
+
--- /dev/null
+From b4ceb0251310b6cd965a0270e9c791bde88d82b5 Mon Sep 17 00:00:00 2001
+From: Hugh Dickins <hughd@google.com>
+Date: Fri, 30 Nov 2018 14:10:25 -0800
+Subject: mm/khugepaged: collapse_shmem() stop if punched or truncated
+
+commit 701270fa193aadf00bdcf607738f64997275d4c7 upstream.
+
+Huge tmpfs testing showed that although collapse_shmem() recognizes a
+concurrently truncated or hole-punched page correctly, its handling of
+holes was liable to refill an emptied extent. Add check to stop that.
+
+Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261522040.2275@eggly.anvils
+Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages")
+Signed-off-by: Hugh Dickins <hughd@google.com>
+Reviewed-by: Matthew Wilcox <willy@infradead.org>
+Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
+Cc: Jerome Glisse <jglisse@redhat.com>
+Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Cc: <stable@vger.kernel.org> [4.8+]
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ mm/khugepaged.c | 15 +++++++++++++++
+ 1 file changed, 15 insertions(+)
+
+diff --git a/mm/khugepaged.c b/mm/khugepaged.c
+index 0a5bb3e8a8a3..d4a06afbeda4 100644
+--- a/mm/khugepaged.c
++++ b/mm/khugepaged.c
+@@ -1352,6 +1352,16 @@ static void collapse_shmem(struct mm_struct *mm,
+ radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
+ int n = min(iter.index, end) - index;
+
++ /*
++ * Stop if extent has been hole-punched, and is now completely
++ * empty (the more obvious i_size_read() check would take an
++ * irq-unsafe seqlock on 32-bit).
++ */
++ if (n >= HPAGE_PMD_NR) {
++ result = SCAN_TRUNCATED;
++ goto tree_locked;
++ }
++
+ /*
+ * Handle holes in the radix tree: charge it from shmem and
+ * insert relevant subpage of new_page into the radix-tree.
+@@ -1463,6 +1473,11 @@ static void collapse_shmem(struct mm_struct *mm,
+ if (result == SCAN_SUCCEED && index < end) {
+ int n = end - index;
+
++ /* Stop if extent has been truncated, and is now empty */
++ if (n >= HPAGE_PMD_NR) {
++ result = SCAN_TRUNCATED;
++ goto tree_locked;
++ }
+ if (!shmem_charge(mapping->host, n)) {
+ result = SCAN_FAIL;
+ goto tree_locked;
+--
+2.17.1
+
--- /dev/null
+From a49315aea21f7f562d235550cebc80f88f6feb85 Mon Sep 17 00:00:00 2001
+From: Hugh Dickins <hughd@google.com>
+Date: Fri, 30 Nov 2018 14:10:43 -0800
+Subject: mm/khugepaged: collapse_shmem() without freezing new_page
+
+commit 87c460a0bded56195b5eb497d44709777ef7b415 upstream.
+
+khugepaged's collapse_shmem() does almost all of its work, to assemble
+the huge new_page from 512 scattered old pages, with the new_page's
+refcount frozen to 0 (and refcounts of all old pages so far also frozen
+to 0). Including shmem_getpage() to read in any which were out on swap,
+memory reclaim if necessary to allocate their intermediate pages, and
+copying over all the data from old to new.
+
+Imagine the frozen refcount as a spinlock held, but without any lock
+debugging to highlight the abuse: it's not good, and under serious load
+heads into lockups - speculative getters of the page are not expecting
+to spin while khugepaged is rescheduled.
+
+One can get a little further under load by hacking around elsewhere; but
+fortunately, freezing the new_page turns out to have been entirely
+unnecessary, with no hacks needed elsewhere.
+
+The huge new_page lock is already held throughout, and guards all its
+subpages as they are brought one by one into the page cache tree; and
+anything reading the data in that page, without the lock, before it has
+been marked PageUptodate, would already be in the wrong. So simply
+eliminate the freezing of the new_page.
+
+Each of the old pages remains frozen with refcount 0 after it has been
+replaced by a new_page subpage in the page cache tree, until they are
+all unfrozen on success or failure: just as before. They could be
+unfrozen sooner, but cause no problem once no longer visible to
+find_get_entry(), filemap_map_pages() and other speculative lookups.
+
+Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261527570.2275@eggly.anvils
+Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages")
+Signed-off-by: Hugh Dickins <hughd@google.com>
+Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
+Cc: Jerome Glisse <jglisse@redhat.com>
+Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Cc: Matthew Wilcox <willy@infradead.org>
+Cc: <stable@vger.kernel.org> [4.8+]
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ mm/khugepaged.c | 19 +++++++------------
+ 1 file changed, 7 insertions(+), 12 deletions(-)
+
+diff --git a/mm/khugepaged.c b/mm/khugepaged.c
+index 0eac4344477a..45bf0e5775f7 100644
+--- a/mm/khugepaged.c
++++ b/mm/khugepaged.c
+@@ -1288,7 +1288,7 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff)
+ * collapse_shmem - collapse small tmpfs/shmem pages into huge one.
+ *
+ * Basic scheme is simple, details are more complex:
+- * - allocate and freeze a new huge page;
++ * - allocate and lock a new huge page;
+ * - scan over radix tree replacing old pages the new one
+ * + swap in pages if necessary;
+ * + fill in gaps;
+@@ -1296,11 +1296,11 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff)
+ * - if replacing succeed:
+ * + copy data over;
+ * + free old pages;
+- * + unfreeze huge page;
++ * + unlock huge page;
+ * - if replacing failed;
+ * + put all pages back and unfreeze them;
+ * + restore gaps in the radix-tree;
+- * + free huge page;
++ * + unlock and free huge page;
+ */
+ static void collapse_shmem(struct mm_struct *mm,
+ struct address_space *mapping, pgoff_t start,
+@@ -1337,13 +1337,11 @@ static void collapse_shmem(struct mm_struct *mm,
+ __SetPageSwapBacked(new_page);
+ new_page->index = start;
+ new_page->mapping = mapping;
+- BUG_ON(!page_ref_freeze(new_page, 1));
+
+ /*
+- * At this point the new_page is 'frozen' (page_count() is zero), locked
+- * and not up-to-date. It's safe to insert it into radix tree, because
+- * nobody would be able to map it or use it in other way until we
+- * unfreeze it.
++ * At this point the new_page is locked and not up-to-date.
++ * It's safe to insert it into the page cache, because nobody would
++ * be able to map it or use it in another way until we unlock it.
+ */
+
+ index = start;
+@@ -1521,9 +1519,8 @@ static void collapse_shmem(struct mm_struct *mm,
+ index++;
+ }
+
+- /* Everything is ready, let's unfreeze the new_page */
+ SetPageUptodate(new_page);
+- page_ref_unfreeze(new_page, HPAGE_PMD_NR);
++ page_ref_add(new_page, HPAGE_PMD_NR - 1);
+ set_page_dirty(new_page);
+ mem_cgroup_commit_charge(new_page, memcg, false, true);
+ lru_cache_add_anon(new_page);
+@@ -1571,8 +1568,6 @@ static void collapse_shmem(struct mm_struct *mm,
+ VM_BUG_ON(nr_none);
+ spin_unlock_irq(&mapping->tree_lock);
+
+- /* Unfreeze new_page, caller would take care about freeing it */
+- page_ref_unfreeze(new_page, 1);
+ mem_cgroup_cancel_charge(new_page, memcg, true);
+ new_page->mapping = NULL;
+ }
+--
+2.17.1
+
--- /dev/null
+From 96fe29655c995eef37c8e6b73d7abfb905eeaa1c Mon Sep 17 00:00:00 2001
+From: Hugh Dickins <hughd@google.com>
+Date: Fri, 30 Nov 2018 14:10:29 -0800
+Subject: mm/khugepaged: fix crashes due to misaccounted holes
+
+commit aaa52e340073b7f4593b3c4ddafcafa70cf838b5 upstream.
+
+Huge tmpfs testing on a shortish file mapped into a pmd-rounded extent
+hit shmem_evict_inode()'s WARN_ON(inode->i_blocks) followed by
+clear_inode()'s BUG_ON(inode->i_data.nrpages) when the file was later
+closed and unlinked.
+
+khugepaged's collapse_shmem() was forgetting to update mapping->nrpages
+on the rollback path, after it had added but then needs to undo some
+holes.
+
+There is indeed an irritating asymmetry between shmem_charge(), whose
+callers want it to increment nrpages after successfully accounting
+blocks, and shmem_uncharge(), when __delete_from_page_cache() already
+decremented nrpages itself: oh well, just add a comment on that to them
+both.
+
+And shmem_recalc_inode() is supposed to be called when the accounting is
+expected to be in balance (so it can deduce from imbalance that reclaim
+discarded some pages): so change shmem_charge() to update nrpages
+earlier (though it's rare for the difference to matter at all).
+
+Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261523450.2275@eggly.anvils
+Fixes: 800d8c63b2e98 ("shmem: add huge pages support")
+Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages")
+Signed-off-by: Hugh Dickins <hughd@google.com>
+Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
+Cc: Jerome Glisse <jglisse@redhat.com>
+Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Cc: Matthew Wilcox <willy@infradead.org>
+Cc: <stable@vger.kernel.org> [4.8+]
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ mm/khugepaged.c | 4 +++-
+ mm/shmem.c | 6 +++++-
+ 2 files changed, 8 insertions(+), 2 deletions(-)
+
+diff --git a/mm/khugepaged.c b/mm/khugepaged.c
+index d4a06afbeda4..be7b0863e33c 100644
+--- a/mm/khugepaged.c
++++ b/mm/khugepaged.c
+@@ -1539,8 +1539,10 @@ static void collapse_shmem(struct mm_struct *mm,
+ *hpage = NULL;
+ } else {
+ /* Something went wrong: rollback changes to the radix-tree */
+- shmem_uncharge(mapping->host, nr_none);
+ spin_lock_irq(&mapping->tree_lock);
++ mapping->nrpages -= nr_none;
++ shmem_uncharge(mapping->host, nr_none);
++
+ radix_tree_for_each_slot(slot, &mapping->page_tree, &iter,
+ start) {
+ if (iter.index >= end)
+diff --git a/mm/shmem.c b/mm/shmem.c
+index fa08f56fd5e5..177fef62cbbd 100644
+--- a/mm/shmem.c
++++ b/mm/shmem.c
+@@ -296,12 +296,14 @@ bool shmem_charge(struct inode *inode, long pages)
+ if (!shmem_inode_acct_block(inode, pages))
+ return false;
+
++ /* nrpages adjustment first, then shmem_recalc_inode() when balanced */
++ inode->i_mapping->nrpages += pages;
++
+ spin_lock_irqsave(&info->lock, flags);
+ info->alloced += pages;
+ inode->i_blocks += pages * BLOCKS_PER_PAGE;
+ shmem_recalc_inode(inode);
+ spin_unlock_irqrestore(&info->lock, flags);
+- inode->i_mapping->nrpages += pages;
+
+ return true;
+ }
+@@ -311,6 +313,8 @@ void shmem_uncharge(struct inode *inode, long pages)
+ struct shmem_inode_info *info = SHMEM_I(inode);
+ unsigned long flags;
+
++ /* nrpages adjustment done by __delete_from_page_cache() or caller */
++
+ spin_lock_irqsave(&info->lock, flags);
+ info->alloced -= pages;
+ inode->i_blocks -= pages * BLOCKS_PER_PAGE;
+--
+2.17.1
+
--- /dev/null
+From 9dd3d399930bf30638d406a686b77b96fd56f129 Mon Sep 17 00:00:00 2001
+From: Hugh Dickins <hughd@google.com>
+Date: Fri, 30 Nov 2018 14:10:39 -0800
+Subject: mm/khugepaged: minor reorderings in collapse_shmem()
+
+commit 042a30824871fa3149b0127009074b75cc25863c upstream.
+
+Several cleanups in collapse_shmem(): most of which probably do not
+really matter, beyond doing things in a more familiar and reassuring
+order. Simplify the failure gotos in the main loop, and on success
+update stats while interrupts still disabled from the last iteration.
+
+Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261526400.2275@eggly.anvils
+Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages")
+Signed-off-by: Hugh Dickins <hughd@google.com>
+Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
+Cc: Jerome Glisse <jglisse@redhat.com>
+Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Cc: Matthew Wilcox <willy@infradead.org>
+Cc: <stable@vger.kernel.org> [4.8+]
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ mm/khugepaged.c | 73 ++++++++++++++++++++-----------------------------
+ 1 file changed, 30 insertions(+), 43 deletions(-)
+
+diff --git a/mm/khugepaged.c b/mm/khugepaged.c
+index f535dbe3f9f5..0eac4344477a 100644
+--- a/mm/khugepaged.c
++++ b/mm/khugepaged.c
+@@ -1333,13 +1333,12 @@ static void collapse_shmem(struct mm_struct *mm,
+ goto out;
+ }
+
++ __SetPageLocked(new_page);
++ __SetPageSwapBacked(new_page);
+ new_page->index = start;
+ new_page->mapping = mapping;
+- __SetPageSwapBacked(new_page);
+- __SetPageLocked(new_page);
+ BUG_ON(!page_ref_freeze(new_page, 1));
+
+-
+ /*
+ * At this point the new_page is 'frozen' (page_count() is zero), locked
+ * and not up-to-date. It's safe to insert it into radix tree, because
+@@ -1368,13 +1367,13 @@ static void collapse_shmem(struct mm_struct *mm,
+ */
+ if (n && !shmem_charge(mapping->host, n)) {
+ result = SCAN_FAIL;
+- break;
++ goto tree_locked;
+ }
+- nr_none += n;
+ for (; index < min(iter.index, end); index++) {
+ radix_tree_insert(&mapping->page_tree, index,
+ new_page + (index % HPAGE_PMD_NR));
+ }
++ nr_none += n;
+
+ /* We are done. */
+ if (index >= end)
+@@ -1390,12 +1389,12 @@ static void collapse_shmem(struct mm_struct *mm,
+ result = SCAN_FAIL;
+ goto tree_unlocked;
+ }
+- spin_lock_irq(&mapping->tree_lock);
+ } else if (trylock_page(page)) {
+ get_page(page);
++ spin_unlock_irq(&mapping->tree_lock);
+ } else {
+ result = SCAN_PAGE_LOCK;
+- break;
++ goto tree_locked;
+ }
+
+ /*
+@@ -1410,11 +1409,10 @@ static void collapse_shmem(struct mm_struct *mm,
+ result = SCAN_TRUNCATED;
+ goto out_unlock;
+ }
+- spin_unlock_irq(&mapping->tree_lock);
+
+ if (isolate_lru_page(page)) {
+ result = SCAN_DEL_PAGE_LRU;
+- goto out_isolate_failed;
++ goto out_unlock;
+ }
+
+ if (page_mapped(page))
+@@ -1436,7 +1434,9 @@ static void collapse_shmem(struct mm_struct *mm,
+ */
+ if (!page_ref_freeze(page, 3)) {
+ result = SCAN_PAGE_COUNT;
+- goto out_lru;
++ spin_unlock_irq(&mapping->tree_lock);
++ putback_lru_page(page);
++ goto out_unlock;
+ }
+
+ /*
+@@ -1452,17 +1452,10 @@ static void collapse_shmem(struct mm_struct *mm,
+ slot = radix_tree_iter_resume(slot, &iter);
+ index++;
+ continue;
+-out_lru:
+- spin_unlock_irq(&mapping->tree_lock);
+- putback_lru_page(page);
+-out_isolate_failed:
+- unlock_page(page);
+- put_page(page);
+- goto tree_unlocked;
+ out_unlock:
+ unlock_page(page);
+ put_page(page);
+- break;
++ goto tree_unlocked;
+ }
+
+ /*
+@@ -1470,7 +1463,7 @@ static void collapse_shmem(struct mm_struct *mm,
+ * This code only triggers if there's nothing in radix tree
+ * beyond 'end'.
+ */
+- if (result == SCAN_SUCCEED && index < end) {
++ if (index < end) {
+ int n = end - index;
+
+ /* Stop if extent has been truncated, and is now empty */
+@@ -1482,7 +1475,6 @@ static void collapse_shmem(struct mm_struct *mm,
+ result = SCAN_FAIL;
+ goto tree_locked;
+ }
+-
+ for (; index < end; index++) {
+ radix_tree_insert(&mapping->page_tree, index,
+ new_page + (index % HPAGE_PMD_NR));
+@@ -1490,14 +1482,19 @@ static void collapse_shmem(struct mm_struct *mm,
+ nr_none += n;
+ }
+
++ __inc_node_page_state(new_page, NR_SHMEM_THPS);
++ if (nr_none) {
++ struct zone *zone = page_zone(new_page);
++
++ __mod_node_page_state(zone->zone_pgdat, NR_FILE_PAGES, nr_none);
++ __mod_node_page_state(zone->zone_pgdat, NR_SHMEM, nr_none);
++ }
++
+ tree_locked:
+ spin_unlock_irq(&mapping->tree_lock);
+ tree_unlocked:
+
+ if (result == SCAN_SUCCEED) {
+- unsigned long flags;
+- struct zone *zone = page_zone(new_page);
+-
+ /*
+ * Replacing old pages with new one has succeed, now we need to
+ * copy the content and free old pages.
+@@ -1511,11 +1508,11 @@ static void collapse_shmem(struct mm_struct *mm,
+ copy_highpage(new_page + (page->index % HPAGE_PMD_NR),
+ page);
+ list_del(&page->lru);
+- unlock_page(page);
+- page_ref_unfreeze(page, 1);
+ page->mapping = NULL;
++ page_ref_unfreeze(page, 1);
+ ClearPageActive(page);
+ ClearPageUnevictable(page);
++ unlock_page(page);
+ put_page(page);
+ index++;
+ }
+@@ -1524,28 +1521,17 @@ static void collapse_shmem(struct mm_struct *mm,
+ index++;
+ }
+
+- local_irq_save(flags);
+- __inc_node_page_state(new_page, NR_SHMEM_THPS);
+- if (nr_none) {
+- __mod_node_page_state(zone->zone_pgdat, NR_FILE_PAGES, nr_none);
+- __mod_node_page_state(zone->zone_pgdat, NR_SHMEM, nr_none);
+- }
+- local_irq_restore(flags);
+-
+- /*
+- * Remove pte page tables, so we can re-faulti
+- * the page as huge.
+- */
+- retract_page_tables(mapping, start);
+-
+ /* Everything is ready, let's unfreeze the new_page */
+- set_page_dirty(new_page);
+ SetPageUptodate(new_page);
+ page_ref_unfreeze(new_page, HPAGE_PMD_NR);
++ set_page_dirty(new_page);
+ mem_cgroup_commit_charge(new_page, memcg, false, true);
+ lru_cache_add_anon(new_page);
+- unlock_page(new_page);
+
++ /*
++ * Remove pte page tables, so we can re-fault the page as huge.
++ */
++ retract_page_tables(mapping, start);
+ *hpage = NULL;
+ } else {
+ /* Something went wrong: rollback changes to the radix-tree */
+@@ -1578,8 +1564,8 @@ static void collapse_shmem(struct mm_struct *mm,
+ slot, page);
+ slot = radix_tree_iter_resume(slot, &iter);
+ spin_unlock_irq(&mapping->tree_lock);
+- putback_lru_page(page);
+ unlock_page(page);
++ putback_lru_page(page);
+ spin_lock_irq(&mapping->tree_lock);
+ }
+ VM_BUG_ON(nr_none);
+@@ -1588,9 +1574,10 @@ static void collapse_shmem(struct mm_struct *mm,
+ /* Unfreeze new_page, caller would take care about freeing it */
+ page_ref_unfreeze(new_page, 1);
+ mem_cgroup_cancel_charge(new_page, memcg, true);
+- unlock_page(new_page);
+ new_page->mapping = NULL;
+ }
++
++ unlock_page(new_page);
+ out:
+ VM_BUG_ON(!list_empty(&pagelist));
+ /* TODO: tracepoints */
+--
+2.17.1
+
--- /dev/null
+mm-huge_memory-rename-freeze_page-to-unmap_page.patch
+mm-huge_memory.c-reorder-operations-in-__split_huge_.patch
+mm-huge_memory-splitting-set-mapping-index-before-un.patch
+mm-huge_memory-fix-lockdep-complaint-on-32-bit-i_siz.patch
+mm-khugepaged-collapse_shmem-stop-if-punched-or-trun.patch
+mm-khugepaged-fix-crashes-due-to-misaccounted-holes.patch
+mm-khugepaged-collapse_shmem-remember-to-clear-holes.patch
+mm-khugepaged-minor-reorderings-in-collapse_shmem.patch
+mm-khugepaged-collapse_shmem-without-freezing-new_pa.patch
+mm-khugepaged-collapse_shmem-do-not-crash-on-compoun.patch
projects / thirdparty / kernel / stable-queue.git / commitdiff
