1 files changed, 248 insertions, 43 deletions

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 418bf01a50ed..e5828875f7bb 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -18,6 +18,7 @@
 #include <linux/bootmem.h>
 #include <linux/sysfs.h>
 #include <linux/slab.h>
+#include <linux/sched/signal.h>
 #include <linux/rmap.h>
 #include <linux/swap.h>
 #include <linux/swapops.h>
@@ -32,6 +33,7 @@
 #include <linux/hugetlb.h>
 #include <linux/hugetlb_cgroup.h>
 #include <linux/node.h>
+#include <linux/userfaultfd_k.h>
 #include "internal.h"
 
 int hugepages_treat_as_movable;
@@ -1051,7 +1053,8 @@ static int __alloc_gigantic_page(unsigned long start_pfn,
 				unsigned long nr_pages)
 {
 	unsigned long end_pfn = start_pfn + nr_pages;
-	return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
+	return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE,
+				  GFP_KERNEL);
 }
 
 static bool pfn_range_valid_gigantic(struct zone *z,
@@ -1773,23 +1776,32 @@ free:
 }
 
 /*
- * When releasing a hugetlb pool reservation, any surplus pages that were
- * allocated to satisfy the reservation must be explicitly freed if they were
- * never used.
- * Called with hugetlb_lock held.
+ * This routine has two main purposes:
+ * 1) Decrement the reservation count (resv_huge_pages) by the value passed
+ *    in unused_resv_pages.  This corresponds to the prior adjustments made
+ *    to the associated reservation map.
+ * 2) Free any unused surplus pages that may have been allocated to satisfy
+ *    the reservation.  As many as unused_resv_pages may be freed.
+ *
+ * Called with hugetlb_lock held.  However, the lock could be dropped (and
+ * reacquired) during calls to cond_resched_lock.  Whenever dropping the lock,
+ * we must make sure nobody else can claim pages we are in the process of
+ * freeing.  Do this by ensuring resv_huge_page always is greater than the
+ * number of huge pages we plan to free when dropping the lock.
  */
 static void return_unused_surplus_pages(struct hstate *h,
 					unsigned long unused_resv_pages)
 {
 	unsigned long nr_pages;
 
-	/* Uncommit the reservation */
-	h->resv_huge_pages -= unused_resv_pages;
-
 	/* Cannot return gigantic pages currently */
 	if (hstate_is_gigantic(h))
-		return;
+		goto out;
 
+	/*
+	 * Part (or even all) of the reservation could have been backed
+	 * by pre-allocated pages. Only free surplus pages.
+	 */
 	nr_pages = min(unused_resv_pages, h->surplus_huge_pages);
 
 	/*
@@ -1799,12 +1811,22 @@ static void return_unused_surplus_pages(struct hstate *h,
 	 * when the nodes with surplus pages have no free pages.
 	 * free_pool_huge_page() will balance the the freed pages across the
 	 * on-line nodes with memory and will handle the hstate accounting.
+	 *
+	 * Note that we decrement resv_huge_pages as we free the pages.  If
+	 * we drop the lock, resv_huge_pages will still be sufficiently large
+	 * to cover subsequent pages we may free.
 	 */
 	while (nr_pages--) {
+		h->resv_huge_pages--;
+		unused_resv_pages--;
 		if (!free_pool_huge_page(h, &node_states[N_MEMORY], 1))
-			break;
+			goto out;
 		cond_resched_lock(&hugetlb_lock);
 	}
+
+out:
+	/* Fully uncommit the reservation */
+	h->resv_huge_pages -= unused_resv_pages;
 }
 
 
@@ -3122,7 +3144,7 @@ static void hugetlb_vm_op_close(struct vm_area_struct *vma)
  * hugegpage VMA.  do_page_fault() is supposed to trap this, so BUG is we get
  * this far.
  */
-static int hugetlb_vm_op_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+static int hugetlb_vm_op_fault(struct vm_fault *vmf)
 {
 	BUG();
 	return 0;
@@ -3286,6 +3308,11 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 	BUG_ON(start & ~huge_page_mask(h));
 	BUG_ON(end & ~huge_page_mask(h));
 
+	/*
+	 * This is a hugetlb vma, all the pte entries should point
+	 * to huge page.
+	 */
+	tlb_remove_check_page_size_change(tlb, sz);
 	tlb_start_vma(tlb, vma);
 	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
 	address = start;
@@ -3336,7 +3363,7 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		}
 
 		pte = huge_ptep_get_and_clear(mm, address, ptep);
-		tlb_remove_tlb_entry(tlb, ptep, address);
+		tlb_remove_huge_tlb_entry(h, tlb, ptep, address);
 		if (huge_pte_dirty(pte))
 			set_page_dirty(page);
 
@@ -3450,15 +3477,17 @@ static void unmap_ref_private(struct mm_struct *mm, struct vm_area_struct *vma,
  * Keep the pte_same checks anyway to make transition from the mutex easier.
  */
 static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
-			unsigned long address, pte_t *ptep, pte_t pte,
-			struct page *pagecache_page, spinlock_t *ptl)
+		       unsigned long address, pte_t *ptep,
+		       struct page *pagecache_page, spinlock_t *ptl)
 {
+	pte_t pte;
 	struct hstate *h = hstate_vma(vma);
 	struct page *old_page, *new_page;
 	int ret = 0, outside_reserve = 0;
 	unsigned long mmun_start;	/* For mmu_notifiers */
 	unsigned long mmun_end;		/* For mmu_notifiers */
 
+	pte = huge_ptep_get(ptep);
 	old_page = pte_page(pte);
 
 retry_avoidcopy:
@@ -3654,6 +3683,38 @@ retry:
 		size = i_size_read(mapping->host) >> huge_page_shift(h);
 		if (idx >= size)
 			goto out;
+
+		/*
+		 * Check for page in userfault range
+		 */
+		if (userfaultfd_missing(vma)) {
+			u32 hash;
+			struct vm_fault vmf = {
+				.vma = vma,
+				.address = address,
+				.flags = flags,
+				/*
+				 * Hard to debug if it ends up being
+				 * used by a callee that assumes
+				 * something about the other
+				 * uninitialized fields... same as in
+				 * memory.c
+				 */
+			};
+
+			/*
+			 * hugetlb_fault_mutex must be dropped before
+			 * handling userfault.  Reacquire after handling
+			 * fault to make calling code simpler.
+			 */
+			hash = hugetlb_fault_mutex_hash(h, mm, vma, mapping,
+							idx, address);
+			mutex_unlock(&hugetlb_fault_mutex_table[hash]);
+			ret = handle_userfault(&vmf, VM_UFFD_MISSING);
+			mutex_lock(&hugetlb_fault_mutex_table[hash]);
+			goto out;
+		}
+
 		page = alloc_huge_page(vma, address, 0);
 		if (IS_ERR(page)) {
 			ret = PTR_ERR(page);
@@ -3711,8 +3772,7 @@ retry:
 		vma_end_reservation(h, vma, address);
 	}
 
-	ptl = huge_pte_lockptr(h, mm, ptep);
-	spin_lock(ptl);
+	ptl = huge_pte_lock(h, mm, ptep);
 	size = i_size_read(mapping->host) >> huge_page_shift(h);
 	if (idx >= size)
 		goto backout;
@@ -3733,7 +3793,7 @@ retry:
 	hugetlb_count_add(pages_per_huge_page(h), mm);
 	if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) {
 		/* Optimization, do the COW without a second fault */
-		ret = hugetlb_cow(mm, vma, address, ptep, new_pte, page, ptl);
+		ret = hugetlb_cow(mm, vma, address, ptep, page, ptl);
 	}
 
 	spin_unlock(ptl);
@@ -3888,8 +3948,8 @@ int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 
 	if (flags & FAULT_FLAG_WRITE) {
 		if (!huge_pte_write(entry)) {
-			ret = hugetlb_cow(mm, vma, address, ptep, entry,
-					pagecache_page, ptl);
+			ret = hugetlb_cow(mm, vma, address, ptep,
+					  pagecache_page, ptl);
 			goto out_put_page;
 		}
 		entry = huge_pte_mkdirty(entry);
@@ -3923,10 +3983,113 @@ out_mutex:
 	return ret;
 }
 
+/*
+ * Used by userfaultfd UFFDIO_COPY.  Based on mcopy_atomic_pte with
+ * modifications for huge pages.
+ */
+int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
+			    pte_t *dst_pte,
+			    struct vm_area_struct *dst_vma,
+			    unsigned long dst_addr,
+			    unsigned long src_addr,
+			    struct page **pagep)
+{
+	int vm_shared = dst_vma->vm_flags & VM_SHARED;
+	struct hstate *h = hstate_vma(dst_vma);
+	pte_t _dst_pte;
+	spinlock_t *ptl;
+	int ret;
+	struct page *page;
+
+	if (!*pagep) {
+		ret = -ENOMEM;
+		page = alloc_huge_page(dst_vma, dst_addr, 0);
+		if (IS_ERR(page))
+			goto out;
+
+		ret = copy_huge_page_from_user(page,
+						(const void __user *) src_addr,
+						pages_per_huge_page(h), false);
+
+		/* fallback to copy_from_user outside mmap_sem */
+		if (unlikely(ret)) {
+			ret = -EFAULT;
+			*pagep = page;
+			/* don't free the page */
+			goto out;
+		}
+	} else {
+		page = *pagep;
+		*pagep = NULL;
+	}
+
+	/*
+	 * The memory barrier inside __SetPageUptodate makes sure that
+	 * preceding stores to the page contents become visible before
+	 * the set_pte_at() write.
+	 */
+	__SetPageUptodate(page);
+	set_page_huge_active(page);
+
+	/*
+	 * If shared, add to page cache
+	 */
+	if (vm_shared) {
+		struct address_space *mapping = dst_vma->vm_file->f_mapping;
+		pgoff_t idx = vma_hugecache_offset(h, dst_vma, dst_addr);
+
+		ret = huge_add_to_page_cache(page, mapping, idx);
+		if (ret)
+			goto out_release_nounlock;
+	}
+
+	ptl = huge_pte_lockptr(h, dst_mm, dst_pte);
+	spin_lock(ptl);
+
+	ret = -EEXIST;
+	if (!huge_pte_none(huge_ptep_get(dst_pte)))
+		goto out_release_unlock;
+
+	if (vm_shared) {
+		page_dup_rmap(page, true);
+	} else {
+		ClearPagePrivate(page);
+		hugepage_add_new_anon_rmap(page, dst_vma, dst_addr);
+	}
+
+	_dst_pte = make_huge_pte(dst_vma, page, dst_vma->vm_flags & VM_WRITE);
+	if (dst_vma->vm_flags & VM_WRITE)
+		_dst_pte = huge_pte_mkdirty(_dst_pte);
+	_dst_pte = pte_mkyoung(_dst_pte);
+
+	set_huge_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
+
+	(void)huge_ptep_set_access_flags(dst_vma, dst_addr, dst_pte, _dst_pte,
+					dst_vma->vm_flags & VM_WRITE);
+	hugetlb_count_add(pages_per_huge_page(h), dst_mm);
+
+	/* No need to invalidate - it was non-present before */
+	update_mmu_cache(dst_vma, dst_addr, dst_pte);
+
+	spin_unlock(ptl);
+	if (vm_shared)
+		unlock_page(page);
+	ret = 0;
+out:
+	return ret;
+out_release_unlock:
+	spin_unlock(ptl);
+out_release_nounlock:
+	if (vm_shared)
+		unlock_page(page);
+	put_page(page);
+	goto out;
+}
+
 long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
 			 struct page **pages, struct vm_area_struct **vmas,
 			 unsigned long *position, unsigned long *nr_pages,
-			 long i, unsigned int flags)
+			 long i, unsigned int flags, int *nonblocking)
 {
 	unsigned long pfn_offset;
 	unsigned long vaddr = *position;
@@ -3989,16 +4152,43 @@ long follow_hugetlb_page(struct mm_struct *mm, struct vm_area_struct *vma,
 		    ((flags & FOLL_WRITE) &&
 		      !huge_pte_write(huge_ptep_get(pte)))) {
 			int ret;
+			unsigned int fault_flags = 0;
 
 			if (pte)
 				spin_unlock(ptl);
-			ret = hugetlb_fault(mm, vma, vaddr,
-				(flags & FOLL_WRITE) ? FAULT_FLAG_WRITE : 0);
-			if (!(ret & VM_FAULT_ERROR))
-				continue;
-
-			remainder = 0;
-			break;
+			if (flags & FOLL_WRITE)
+				fault_flags |= FAULT_FLAG_WRITE;
+			if (nonblocking)
+				fault_flags |= FAULT_FLAG_ALLOW_RETRY;
+			if (flags & FOLL_NOWAIT)
+				fault_flags |= FAULT_FLAG_ALLOW_RETRY |
+					FAULT_FLAG_RETRY_NOWAIT;
+			if (flags & FOLL_TRIED) {
+				VM_WARN_ON_ONCE(fault_flags &
+						FAULT_FLAG_ALLOW_RETRY);
+				fault_flags |= FAULT_FLAG_TRIED;
+			}
+			ret = hugetlb_fault(mm, vma, vaddr, fault_flags);
+			if (ret & VM_FAULT_ERROR) {
+				remainder = 0;
+				break;
+			}
+			if (ret & VM_FAULT_RETRY) {
+				if (nonblocking)
+					*nonblocking = 0;
+				*nr_pages = 0;
+				/*
+				 * VM_FAULT_RETRY must not return an
+				 * error, it will return zero
+				 * instead.
+				 *
+				 * No need to update "position" as the
+				 * caller will not check it after
+				 * *nr_pages is set to 0.
+				 */
+				return i;
+			}
+			continue;
 		}
 
 		pfn_offset = (vaddr & ~huge_page_mask(h)) >> PAGE_SHIFT;
@@ -4027,6 +4217,11 @@ same_page:
 		spin_unlock(ptl);
 	}
 	*nr_pages = remainder;
+	/*
+	 * setting position is actually required only if remainder is
+	 * not zero but it's faster not to add a "if (remainder)"
+	 * branch.
+	 */
 	*position = vaddr;
 
 	return i ? i : -EFAULT;
@@ -4208,7 +4403,9 @@ int hugetlb_reserve_pages(struct inode *inode,
 	return 0;
 out_err:
 	if (!vma || vma->vm_flags & VM_MAYSHARE)
-		region_abort(resv_map, from, to);
+		/* Don't call region_abort if region_chg failed */
+		if (chg >= 0)
+			region_abort(resv_map, from, to);
 	if (vma && is_vma_resv_set(vma, HPAGE_RESV_OWNER))
 		kref_put(&resv_map->refs, resv_map_release);
 	return ret;
@@ -4330,8 +4527,7 @@ pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
 	if (!spte)
 		goto out;
 
-	ptl = huge_pte_lockptr(hstate_vma(vma), mm, spte);
-	spin_lock(ptl);
+	ptl = huge_pte_lock(hstate_vma(vma), mm, spte);
 	if (pud_none(*pud)) {
 		pud_populate(mm, pud,
 				(pmd_t *)((unsigned long)spte & PAGE_MASK));
@@ -4361,7 +4557,8 @@ out:
 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
 {
 	pgd_t *pgd = pgd_offset(mm, *addr);
-	pud_t *pud = pud_offset(pgd, *addr);
+	p4d_t *p4d = p4d_offset(pgd, *addr);
+	pud_t *pud = pud_offset(p4d, *addr);
 
 	BUG_ON(page_count(virt_to_page(ptep)) == 0);
 	if (page_count(virt_to_page(ptep)) == 1)
@@ -4392,11 +4589,13 @@ pte_t *huge_pte_alloc(struct mm_struct *mm,
 			unsigned long addr, unsigned long sz)
 {
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
 	pte_t *pte = NULL;
 
 	pgd = pgd_offset(mm, addr);
-	pud = pud_alloc(mm, pgd, addr);
+	p4d = p4d_offset(pgd, addr);
+	pud = pud_alloc(mm, p4d, addr);
 	if (pud) {
 		if (sz == PUD_SIZE) {
 			pte = (pte_t *)pud;
@@ -4416,18 +4615,22 @@ pte_t *huge_pte_alloc(struct mm_struct *mm,
 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
 {
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
-	pmd_t *pmd = NULL;
+	pmd_t *pmd;
 
 	pgd = pgd_offset(mm, addr);
-	if (pgd_present(*pgd)) {
-		pud = pud_offset(pgd, addr);
-		if (pud_present(*pud)) {
-			if (pud_huge(*pud))
-				return (pte_t *)pud;
-			pmd = pmd_offset(pud, addr);
-		}
-	}
+	if (!pgd_present(*pgd))
+		return NULL;
+	p4d = p4d_offset(pgd, addr);
+	if (!p4d_present(*p4d))
+		return NULL;
+	pud = pud_offset(p4d, addr);
+	if (!pud_present(*pud))
+		return NULL;
+	if (pud_huge(*pud))
+		return (pte_t *)pud;
+	pmd = pmd_offset(pud, addr);
 	return (pte_t *) pmd;
 }
 
@@ -4450,6 +4653,7 @@ follow_huge_pmd(struct mm_struct *mm, unsigned long address,
 {
 	struct page *page = NULL;
 	spinlock_t *ptl;
+	pte_t pte;
 retry:
 	ptl = pmd_lockptr(mm, pmd);
 	spin_lock(ptl);
@@ -4459,12 +4663,13 @@ retry:
 	 */
 	if (!pmd_huge(*pmd))
 		goto out;
-	if (pmd_present(*pmd)) {
+	pte = huge_ptep_get((pte_t *)pmd);
+	if (pte_present(pte)) {
 		page = pmd_page(*pmd) + ((address & ~PMD_MASK) >> PAGE_SHIFT);
 		if (flags & FOLL_GET)
 			get_page(page);
 	} else {
-		if (is_hugetlb_entry_migration(huge_ptep_get((pte_t *)pmd))) {
+		if (is_hugetlb_entry_migration(pte)) {
 			spin_unlock(ptl);
 			__migration_entry_wait(mm, (pte_t *)pmd, ptl);
 			goto retry;