Merge branch 'akpm' (patches from Andrew Morton)

Merge fixes from Andrew Morton:
 "10 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm: hugetlb: fix copy_hugetlb_page_range()
  simple_xattr: permit 0-size extended attributes
  mm/fs: fix pessimization in hole-punching pagecache
  shmem: fix splicing from a hole while it's punched
  shmem: fix faulting into a hole, not taking i_mutex
  mm: do not call do_fault_around for non-linear fault
  sh: also try passing -m4-nofpu for SH2A builds
  zram: avoid lockdep splat by revalidate_disk
  mm/rmap.c: fix pgoff calculation to handle hugepage correctly
  coredump: fix the setting of PF_DUMPCORE

11 files changed, 117 insertions, 55 deletions

diff --git a/arch/sh/Makefile b/arch/sh/Makefile
index d4d16e4be07c..bf5b3f5f4962 100644
--- a/arch/sh/Makefile
+++ b/arch/sh/Makefile
@@ -32,7 +32,8 @@ endif
 
 cflags-$(CONFIG_CPU_SH2)                := $(call cc-option,-m2,)
 cflags-$(CONFIG_CPU_SH2A)               += $(call cc-option,-m2a,) \
-                                           $(call cc-option,-m2a-nofpu,)
+                                           $(call cc-option,-m2a-nofpu,) \
+                                           $(call cc-option,-m4-nofpu,)
 cflags-$(CONFIG_CPU_SH3)                := $(call cc-option,-m3,)
 cflags-$(CONFIG_CPU_SH4)                := $(call cc-option,-m4,) \
         $(call cc-option,-mno-implicit-fp,-m4-nofpu)
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 089e72cd37be..36e54be402df 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -622,11 +622,18 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
         memset(&zram->stats, 0, sizeof(zram->stats));
 
         zram->disksize = 0;
-        if (reset_capacity) {
+        if (reset_capacity)
                 set_capacity(zram->disk, 0);
-                revalidate_disk(zram->disk);
-        }
+
         up_write(&zram->init_lock);
+
+        /*
+         * Revalidate disk out of the init_lock to avoid lockdep splat.
+         * It's okay because disk's capacity is protected by init_lock
+         * so that revalidate_disk always sees up-to-date capacity.
+         */
+        if (reset_capacity)
+                revalidate_disk(zram->disk);
 }
 
 static ssize_t disksize_store(struct device *dev,
@@ -666,8 +673,15 @@ static ssize_t disksize_store(struct device *dev,
         zram->comp = comp;
         zram->disksize = disksize;
         set_capacity(zram->disk, zram->disksize >> SECTOR_SHIFT);
-        revalidate_disk(zram->disk);
         up_write(&zram->init_lock);
+
+        /*
+         * Revalidate disk out of the init_lock to avoid lockdep splat.
+         * It's okay because disk's capacity is protected by init_lock
+         * so that revalidate_disk always sees up-to-date capacity.
+         */
+        revalidate_disk(zram->disk);
+
         return len;
 
 out_destroy_comp:
diff --git a/fs/coredump.c b/fs/coredump.c
index 0b2528fb640e..a93f7e6ea4cf 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -306,7 +306,7 @@ static int zap_threads(struct task_struct *tsk, struct mm_struct *mm,
         if (unlikely(nr < 0))
                 return nr;
 
-        tsk->flags = PF_DUMPCORE;
+        tsk->flags |= PF_DUMPCORE;
         if (atomic_read(&mm->mm_users) == nr + 1)
                 goto done;
         /*
diff --git a/fs/xattr.c b/fs/xattr.c
index 3377dff18404..c69e6d43a0d2 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -843,7 +843,7 @@ struct simple_xattr *simple_xattr_alloc(const void *value, size_t size)
 
         /* wrap around? */
         len = sizeof(*new_xattr) + size;
-        if (len <= sizeof(*new_xattr))
+        if (len < sizeof(*new_xattr))
                 return NULL;
 
         new_xattr = kmalloc(len, GFP_KERNEL);
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 0a97b583ee8d..e1474ae18c88 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -399,6 +399,18 @@ static inline struct page *read_mapping_page(struct address_space *mapping,
 }
 
 /*
+ * Get the offset in PAGE_SIZE.
+ * (TODO: hugepage should have ->index in PAGE_SIZE)
+ */
+static inline pgoff_t page_to_pgoff(struct page *page)
+{
+        if (unlikely(PageHeadHuge(page)))
+                return page->index << compound_order(page);
+        else
+                return page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
+}
+
+/*
  * Return byte-offset into filesystem object for page.
  */
 static inline loff_t page_offset(struct page *page)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 2024bbd573d2..9221c02ed9e2 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2604,6 +2604,7 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
                 } else {
                         if (cow)
                                 huge_ptep_set_wrprotect(src, addr, src_pte);
+                        entry = huge_ptep_get(src_pte);
                         ptepage = pte_page(entry);
                         get_page(ptepage);
                         page_dup_rmap(ptepage);
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index c6399e328931..7211a73ba14d 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -435,7 +435,7 @@ static void collect_procs_anon(struct page *page, struct list_head *to_kill,
         if (av == NULL) /* Not actually mapped anymore */
                 return;
 
-        pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
+        pgoff = page_to_pgoff(page);
         read_lock(&tasklist_lock);
         for_each_process (tsk) {
                 struct anon_vma_chain *vmac;
@@ -469,7 +469,7 @@ static void collect_procs_file(struct page *page, struct list_head *to_kill,
         mutex_lock(&mapping->i_mmap_mutex);
         read_lock(&tasklist_lock);
         for_each_process(tsk) {
-                pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
+                pgoff_t pgoff = page_to_pgoff(page);
                 struct task_struct *t = task_early_kill(tsk, force_early);
 
                 if (!t)
diff --git a/mm/memory.c b/mm/memory.c
index d67fd9fcf1f2..7e8d8205b610 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2882,7 +2882,8 @@ static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma,
          * if page by the offset is not ready to be mapped (cold cache or
          * something).
          */
-        if (vma->vm_ops->map_pages && fault_around_pages() > 1) {
+        if (vma->vm_ops->map_pages && !(flags & FAULT_FLAG_NONLINEAR) &&
+            fault_around_pages() > 1) {
                 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
                 do_fault_around(vma, address, pte, pgoff, flags);
                 if (!pte_same(*pte, orig_pte))
diff --git a/mm/rmap.c b/mm/rmap.c
index b7e94ebbd09e..22a4a7699cdb 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -517,11 +517,7 @@ void page_unlock_anon_vma_read(struct anon_vma *anon_vma)
 static inline unsigned long
 __vma_address(struct page *page, struct vm_area_struct *vma)
 {
-        pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
-
-        if (unlikely(is_vm_hugetlb_page(vma)))
-                pgoff = page->index << huge_page_order(page_hstate(page));
-
+        pgoff_t pgoff = page_to_pgoff(page);
         return vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
 }
 
@@ -1639,7 +1635,7 @@ static struct anon_vma *rmap_walk_anon_lock(struct page *page,
 static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc)
 {
         struct anon_vma *anon_vma;
-        pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
+        pgoff_t pgoff = page_to_pgoff(page);
         struct anon_vma_chain *avc;
         int ret = SWAP_AGAIN;
 
@@ -1680,7 +1676,7 @@ static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc)
 static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
 {
         struct address_space *mapping = page->mapping;
-        pgoff_t pgoff = page->index << compound_order(page);
+        pgoff_t pgoff = page_to_pgoff(page);
         struct vm_area_struct *vma;
         int ret = SWAP_AGAIN;
 
diff --git a/mm/shmem.c b/mm/shmem.c
index 1140f49b6ded..af68b15a8fc1 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -85,7 +85,7 @@ static struct vfsmount *shm_mnt;
  * a time): we would prefer not to enlarge the shmem inode just for that.
  */
 struct shmem_falloc {
-        int     mode;           /* FALLOC_FL mode currently operating */
+        wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
         pgoff_t start;          /* start of range currently being fallocated */
         pgoff_t next;           /* the next page offset to be fallocated */
         pgoff_t nr_falloced;    /* how many new pages have been fallocated */
@@ -468,23 +468,20 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
                 return;
 
         index = start;
-        for ( ; ; ) {
+        while (index < end) {
                 cond_resched();
 
                 pvec.nr = find_get_entries(mapping, index,
                                 min(end - index, (pgoff_t)PAGEVEC_SIZE),
                                 pvec.pages, indices);
                 if (!pvec.nr) {
-                        if (index == start || unfalloc)
+                        /* If all gone or hole-punch or unfalloc, we're done */
+                        if (index == start || end != -1)
                                 break;
+                        /* But if truncating, restart to make sure all gone */
                         index = start;
                         continue;
                 }
-                if ((index == start || unfalloc) && indices[0] >= end) {
-                        pagevec_remove_exceptionals(&pvec);
-                        pagevec_release(&pvec);
-                        break;
-                }
                 mem_cgroup_uncharge_start();
                 for (i = 0; i < pagevec_count(&pvec); i++) {
                         struct page *page = pvec.pages[i];
@@ -496,8 +493,12 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
                         if (radix_tree_exceptional_entry(page)) {
                                 if (unfalloc)
                                         continue;
-                                nr_swaps_freed += !shmem_free_swap(mapping,
-                                                                index, page);
+                                if (shmem_free_swap(mapping, index, page)) {
+                                        /* Swap was replaced by page: retry */
+                                        index--;
+                                        break;
+                                }
+                                nr_swaps_freed++;
                                 continue;
                         }
 
@@ -506,6 +507,11 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
                                 if (page->mapping == mapping) {
                                         VM_BUG_ON_PAGE(PageWriteback(page), page);
                                         truncate_inode_page(mapping, page);
+                                } else {
+                                        /* Page was replaced by swap: retry */
+                                        unlock_page(page);
+                                        index--;
+                                        break;
                                 }
                         }
                         unlock_page(page);
@@ -760,7 +766,7 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
                         spin_lock(&inode->i_lock);
                         shmem_falloc = inode->i_private;
                         if (shmem_falloc &&
-                            !shmem_falloc->mode &&
+                            !shmem_falloc->waitq &&
                             index >= shmem_falloc->start &&
                             index < shmem_falloc->next)
                                 shmem_falloc->nr_unswapped++;
@@ -1248,38 +1254,58 @@ static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
          * Trinity finds that probing a hole which tmpfs is punching can
          * prevent the hole-punch from ever completing: which in turn
          * locks writers out with its hold on i_mutex.  So refrain from
-         * faulting pages into the hole while it's being punched, and
-         * wait on i_mutex to be released if vmf->flags permits.
+         * faulting pages into the hole while it's being punched.  Although
+         * shmem_undo_range() does remove the additions, it may be unable to
+         * keep up, as each new page needs its own unmap_mapping_range() call,
+         * and the i_mmap tree grows ever slower to scan if new vmas are added.
+         *
+         * It does not matter if we sometimes reach this check just before the
+         * hole-punch begins, so that one fault then races with the punch:
+         * we just need to make racing faults a rare case.
+         *
+         * The implementation below would be much simpler if we just used a
+         * standard mutex or completion: but we cannot take i_mutex in fault,
+         * and bloating every shmem inode for this unlikely case would be sad.
          */
         if (unlikely(inode->i_private)) {
                 struct shmem_falloc *shmem_falloc;
 
                 spin_lock(&inode->i_lock);
                 shmem_falloc = inode->i_private;
-                if (!shmem_falloc ||
-                    shmem_falloc->mode != FALLOC_FL_PUNCH_HOLE ||
-                    vmf->pgoff < shmem_falloc->start ||
-                    vmf->pgoff >= shmem_falloc->next)
-                        shmem_falloc = NULL;
-                spin_unlock(&inode->i_lock);
-                /*
-                 * i_lock has protected us from taking shmem_falloc seriously
-                 * once return from shmem_fallocate() went back up that stack.
-                 * i_lock does not serialize with i_mutex at all, but it does
-                 * not matter if sometimes we wait unnecessarily, or sometimes
-                 * miss out on waiting: we just need to make those cases rare.
-                 */
-                if (shmem_falloc) {
+                if (shmem_falloc &&
+                    shmem_falloc->waitq &&
+                    vmf->pgoff >= shmem_falloc->start &&
+                    vmf->pgoff < shmem_falloc->next) {
+                        wait_queue_head_t *shmem_falloc_waitq;
+                        DEFINE_WAIT(shmem_fault_wait);
+
+                        ret = VM_FAULT_NOPAGE;
                         if ((vmf->flags & FAULT_FLAG_ALLOW_RETRY) &&
                            !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {
+                                /* It's polite to up mmap_sem if we can */
                                 up_read(&vma->vm_mm->mmap_sem);
-                                mutex_lock(&inode->i_mutex);
-                                mutex_unlock(&inode->i_mutex);
-                                return VM_FAULT_RETRY;
+                                ret = VM_FAULT_RETRY;
                         }
-                        /* cond_resched? Leave that to GUP or return to user */
-                        return VM_FAULT_NOPAGE;
+
+                        shmem_falloc_waitq = shmem_falloc->waitq;
+                        prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait,
+                                        TASK_UNINTERRUPTIBLE);
+                        spin_unlock(&inode->i_lock);
+                        schedule();
+
+                        /*
+                         * shmem_falloc_waitq points into the shmem_fallocate()
+                         * stack of the hole-punching task: shmem_falloc_waitq
+                         * is usually invalid by the time we reach here, but
+                         * finish_wait() does not dereference it in that case;
+                         * though i_lock needed lest racing with wake_up_all().
+                         */
+                        spin_lock(&inode->i_lock);
+                        finish_wait(shmem_falloc_waitq, &shmem_fault_wait);
+                        spin_unlock(&inode->i_lock);
+                        return ret;
                 }
+                spin_unlock(&inode->i_lock);
         }
 
         error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
@@ -1774,13 +1800,13 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
 
         mutex_lock(&inode->i_mutex);
 
-        shmem_falloc.mode = mode & ~FALLOC_FL_KEEP_SIZE;
-
         if (mode & FALLOC_FL_PUNCH_HOLE) {
                 struct address_space *mapping = file->f_mapping;
                 loff_t unmap_start = round_up(offset, PAGE_SIZE);
                 loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
+                DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
 
+                shmem_falloc.waitq = &shmem_falloc_waitq;
                 shmem_falloc.start = unmap_start >> PAGE_SHIFT;
                 shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
                 spin_lock(&inode->i_lock);
@@ -1792,8 +1818,13 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
                                             1 + unmap_end - unmap_start, 0);
                 shmem_truncate_range(inode, offset, offset + len - 1);
                 /* No need to unmap again: hole-punching leaves COWed pages */
+
+                spin_lock(&inode->i_lock);
+                inode->i_private = NULL;
+                wake_up_all(&shmem_falloc_waitq);
+                spin_unlock(&inode->i_lock);
                 error = 0;
-                goto undone;
+                goto out;
         }
 
         /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
@@ -1809,6 +1840,7 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset,
                 goto out;
         }
 
+        shmem_falloc.waitq = NULL;
         shmem_falloc.start = start;
         shmem_falloc.next  = start;
         shmem_falloc.nr_falloced = 0;
diff --git a/mm/truncate.c b/mm/truncate.c
index 6a78c814bebf..eda247307164 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -355,14 +355,16 @@ void truncate_inode_pages_range(struct address_space *mapping,
         for ( ; ; ) {
                 cond_resched();
                 if (!pagevec_lookup_entries(&pvec, mapping, index,
-                        min(end - index, (pgoff_t)PAGEVEC_SIZE),
-                        indices)) {
+                        min(end - index, (pgoff_t)PAGEVEC_SIZE), indices)) {
+                        /* If all gone from start onwards, we're done */
                         if (index == start)
                                 break;
+                        /* Otherwise restart to make sure all gone */
                         index = start;
                         continue;
                 }
                 if (index == start && indices[0] >= end) {
+                        /* All gone out of hole to be punched, we're done */
                         pagevec_remove_exceptionals(&pvec);
                         pagevec_release(&pvec);
                         break;
@@ -373,8 +375,11 @@ void truncate_inode_pages_range(struct address_space *mapping,
 
                         /* We rely upon deletion not changing page->index */
                         index = indices[i];
-                        if (index >= end)
+                        if (index >= end) {
+                                /* Restart punch to make sure all gone */
+                                index = start - 1;
                                 break;
+                        }
 
                         if (radix_tree_exceptional_entry(page)) {
                                 clear_exceptional_entry(mapping, index, page);