Merge branch 'akpm' (fixes from Andrew)

Merge patches from Andrew Morton:
 "13 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  mm: place page->pmd_huge_pte to right union
  MAINTAINERS: add keyboard driver to Hyper-V file list
  x86, mm: do not leak page->ptl for pmd page tables
  ipc,shm: correct error return value in shmctl (SHM_UNLOCK)
  mm, mempolicy: silence gcc warning
  block/partitions/efi.c: fix bound check
  ARM: drivers/rtc/rtc-at91rm9200.c: disable interrupts at shutdown
  mm: hugetlbfs: fix hugetlbfs optimization
  kernel: remove CONFIG_USE_GENERIC_SMP_HELPERS cleanly
  ipc,shm: fix shm_file deletion races
  mm: thp: give transparent hugepage code a separate copy_page
  checkpatch: fix "Use of uninitialized value" warnings
  configfs: fix race between dentry put and lookup

16 files changed, 227 insertions, 124 deletions

diff --git a/Documentation/vm/split_page_table_lock b/Documentation/vm/split_page_table_lock
index 7521d367f21..6dea4fd5c96 100644
--- a/Documentation/vm/split_page_table_lock
+++ b/Documentation/vm/split_page_table_lock
@@ -63,9 +63,9 @@ levels.
 PMD split lock enabling requires pgtable_pmd_page_ctor() call on PMD table
 allocation and pgtable_pmd_page_dtor() on freeing.
 
-Allocation usually happens in pmd_alloc_one(), freeing in pmd_free(), but
-make sure you cover all PMD table allocation / freeing paths: i.e X86_PAE
-preallocate few PMDs on pgd_alloc().
+Allocation usually happens in pmd_alloc_one(), freeing in pmd_free() and
+pmd_free_tlb(), but make sure you cover all PMD table allocation / freeing
+paths: i.e X86_PAE preallocate few PMDs on pgd_alloc().
 
 With everything in place you can set CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK.
 
diff --git a/MAINTAINERS b/MAINTAINERS
index 8d98e54f2bf..d9c97dce663 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4065,6 +4065,7 @@ F:	arch/x86/include/uapi/asm/hyperv.h
 F:	arch/x86/kernel/cpu/mshyperv.c
 F:	drivers/hid/hid-hyperv.c
 F:	drivers/hv/
+F:	drivers/input/serio/hyperv-keyboard.c
 F:	drivers/net/hyperv/
 F:	drivers/scsi/storvsc_drv.c
 F:	drivers/video/hyperv_fb.c
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 36aa999b263..c96314abd14 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -61,6 +61,7 @@ void ___pte_free_tlb(struct mmu_gather *tlb, struct page *pte)
 #if PAGETABLE_LEVELS > 2
 void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
 {
+	struct page *page = virt_to_page(pmd);
 	paravirt_release_pmd(__pa(pmd) >> PAGE_SHIFT);
 	/*
 	 * NOTE! For PAE, any changes to the top page-directory-pointer-table
@@ -69,7 +70,8 @@ void ___pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
 #ifdef CONFIG_X86_PAE
 	tlb->need_flush_all = 1;
 #endif
-	tlb_remove_page(tlb, virt_to_page(pmd));
+	pgtable_pmd_page_dtor(page);
+	tlb_remove_page(tlb, page);
 }
 
 #if PAGETABLE_LEVELS > 3
diff --git a/block/partitions/efi.c b/block/partitions/efi.c
index a8287b49d06..dc51f467a56 100644
--- a/block/partitions/efi.c
+++ b/block/partitions/efi.c
@@ -96,6 +96,7 @@
  * - Code works, detects all the partitions.
  *
  ************************************************************/
+#include <linux/kernel.h>
 #include <linux/crc32.h>
 #include <linux/ctype.h>
 #include <linux/math64.h>
@@ -715,8 +716,8 @@ int efi_partition(struct parsed_partitions *state)
 		efi_guid_unparse(&ptes[i].unique_partition_guid, info->uuid);
 
 		/* Naively convert UTF16-LE to 7 bits. */
-		label_max = min(sizeof(info->volname) - 1,
-				sizeof(ptes[i].partition_name));
+		label_max = min(ARRAY_SIZE(info->volname) - 1,
+				ARRAY_SIZE(ptes[i].partition_name));
 		info->volname[label_max] = 0;
 		while (label_count < label_max) {
 			u8 c = ptes[i].partition_name[label_count] & 0xff;
diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index b5d842370cc..ea192ec029c 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -223,7 +223,7 @@ static void null_softirq_done_fn(struct request *rq)
 	blk_end_request_all(rq, 0);
 }
 
-#if defined(CONFIG_SMP) && defined(CONFIG_USE_GENERIC_SMP_HELPERS)
+#ifdef CONFIG_SMP
 
 static void null_ipi_cmd_end_io(void *data)
 {
@@ -260,7 +260,7 @@ static void null_cmd_end_ipi(struct nullb_cmd *cmd)
 	put_cpu();
 }
 
-#endif /* CONFIG_SMP && CONFIG_USE_GENERIC_SMP_HELPERS */
+#endif /* CONFIG_SMP */
 
 static inline void null_handle_cmd(struct nullb_cmd *cmd)
 {
@@ -270,7 +270,7 @@ static inline void null_handle_cmd(struct nullb_cmd *cmd)
 		end_cmd(cmd);
 		break;
 	case NULL_IRQ_SOFTIRQ:
-#if defined(CONFIG_SMP) && defined(CONFIG_USE_GENERIC_SMP_HELPERS)
+#ifdef CONFIG_SMP
 		null_cmd_end_ipi(cmd);
 #else
 		end_cmd(cmd);
@@ -571,7 +571,7 @@ static int __init null_init(void)
 {
 	unsigned int i;
 
-#if !defined(CONFIG_SMP) || !defined(CONFIG_USE_GENERIC_SMP_HELPERS)
+#if !defined(CONFIG_SMP)
 	if (irqmode == NULL_IRQ_SOFTIRQ) {
 		pr_warn("null_blk: softirq completions not available.\n");
 		pr_warn("null_blk: using direct completions.\n");
diff --git a/drivers/rtc/rtc-at91rm9200.c b/drivers/rtc/rtc-at91rm9200.c
index 8b2cd8a5a2f..c0da95e9570 100644
--- a/drivers/rtc/rtc-at91rm9200.c
+++ b/drivers/rtc/rtc-at91rm9200.c
@@ -428,6 +428,14 @@ static int __exit at91_rtc_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static void at91_rtc_shutdown(struct platform_device *pdev)
+{
+	/* Disable all interrupts */
+	at91_rtc_write(AT91_RTC_IDR, AT91_RTC_ACKUPD | AT91_RTC_ALARM |
+					AT91_RTC_SECEV | AT91_RTC_TIMEV |
+					AT91_RTC_CALEV);
+}
+
 #ifdef CONFIG_PM_SLEEP
 
 /* AT91RM9200 RTC Power management control */
@@ -466,6 +474,7 @@ static SIMPLE_DEV_PM_OPS(at91_rtc_pm_ops, at91_rtc_suspend, at91_rtc_resume);
 
 static struct platform_driver at91_rtc_driver = {
 	.remove		= __exit_p(at91_rtc_remove),
+	.shutdown	= at91_rtc_shutdown,
 	.driver		= {
 		.name	= "at91_rtc",
 		.owner	= THIS_MODULE,
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index 4522e075577..e081acbac2e 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -56,10 +56,19 @@ static void configfs_d_iput(struct dentry * dentry,
 	struct configfs_dirent *sd = dentry->d_fsdata;
 
 	if (sd) {
-		BUG_ON(sd->s_dentry != dentry);
 		/* Coordinate with configfs_readdir */
 		spin_lock(&configfs_dirent_lock);
-		sd->s_dentry = NULL;
+		/* Coordinate with configfs_attach_attr where will increase
+		 * sd->s_count and update sd->s_dentry to new allocated one.
+		 * Only set sd->dentry to null when this dentry is the only
+		 * sd owner.
+		 * If not do so, configfs_d_iput may run just after
+		 * configfs_attach_attr and set sd->s_dentry to null
+		 * even it's still in use.
+		 */
+		if (atomic_read(&sd->s_count) <= 2)
+			sd->s_dentry = NULL;
+
 		spin_unlock(&configfs_dirent_lock);
 		configfs_put(sd);
 	}
@@ -416,8 +425,11 @@ static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * den
 	struct configfs_attribute * attr = sd->s_element;
 	int error;
 
+	spin_lock(&configfs_dirent_lock);
 	dentry->d_fsdata = configfs_get(sd);
 	sd->s_dentry = dentry;
+	spin_unlock(&configfs_dirent_lock);
+
 	error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG,
 				configfs_init_file);
 	if (error) {
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index acd2010328f..9649ff0c63f 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -31,6 +31,7 @@ struct hugepage_subpool *hugepage_new_subpool(long nr_blocks);
 void hugepage_put_subpool(struct hugepage_subpool *spool);
 
 int PageHuge(struct page *page);
+int PageHeadHuge(struct page *page_head);
 
 void reset_vma_resv_huge_pages(struct vm_area_struct *vma);
 int hugetlb_sysctl_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *);
@@ -69,7 +70,6 @@ int dequeue_hwpoisoned_huge_page(struct page *page);
 bool isolate_huge_page(struct page *page, struct list_head *list);
 void putback_active_hugepage(struct page *page);
 bool is_hugepage_active(struct page *page);
-void copy_huge_page(struct page *dst, struct page *src);
 
 #ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
 pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud);
@@ -104,6 +104,11 @@ static inline int PageHuge(struct page *page)
 	return 0;
 }
 
+static inline int PageHeadHuge(struct page *page_head)
+{
+	return 0;
+}
+
 static inline void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
 {
 }
@@ -140,9 +145,6 @@ static inline int dequeue_hwpoisoned_huge_page(struct page *page)
 #define isolate_huge_page(p, l) false
 #define putback_active_hugepage(p)	do {} while (0)
 #define is_hugepage_active(x)	false
-static inline void copy_huge_page(struct page *dst, struct page *src)
-{
-}
 
 static inline unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
 		unsigned long address, unsigned long end, pgprot_t newprot)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 10f5a7272b8..011eb85d7b0 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -65,9 +65,6 @@ struct page {
 						 * this page is only used to
 						 * free other pages.
 						 */
-#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && USE_SPLIT_PMD_PTLOCKS
-		pgtable_t pmd_huge_pte; /* protected by page->ptl */
-#endif
 		};
 
 		union {
@@ -135,6 +132,9 @@ struct page {
 
 		struct list_head list;	/* slobs list of pages */
 		struct slab *slab_page; /* slab fields */
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && USE_SPLIT_PMD_PTLOCKS
+		pgtable_t pmd_huge_pte; /* protected by page->ptl */
+#endif
 	};
 
 	/* Remainder is not double word aligned */
diff --git a/ipc/shm.c b/ipc/shm.c
index d69739610fd..7a51443a51d 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -208,15 +208,18 @@ static void shm_open(struct vm_area_struct *vma)
  */
 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 {
+	struct file *shm_file;
+
+	shm_file = shp->shm_file;
+	shp->shm_file = NULL;
 	ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
 	shm_rmid(ns, shp);
 	shm_unlock(shp);
-	if (!is_file_hugepages(shp->shm_file))
-		shmem_lock(shp->shm_file, 0, shp->mlock_user);
+	if (!is_file_hugepages(shm_file))
+		shmem_lock(shm_file, 0, shp->mlock_user);
 	else if (shp->mlock_user)
-		user_shm_unlock(file_inode(shp->shm_file)->i_size,
-						shp->mlock_user);
-	fput (shp->shm_file);
+		user_shm_unlock(file_inode(shm_file)->i_size, shp->mlock_user);
+	fput(shm_file);
 	ipc_rcu_putref(shp, shm_rcu_free);
 }
 
@@ -974,15 +977,25 @@ SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
 		ipc_lock_object(&shp->shm_perm);
 		if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
 			kuid_t euid = current_euid();
-			err = -EPERM;
 			if (!uid_eq(euid, shp->shm_perm.uid) &&
-			    !uid_eq(euid, shp->shm_perm.cuid))
+			    !uid_eq(euid, shp->shm_perm.cuid)) {
+				err = -EPERM;
 				goto out_unlock0;
-			if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK))
+			}
+			if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) {
+				err = -EPERM;
 				goto out_unlock0;
+			}
 		}
 
 		shm_file = shp->shm_file;
+
+		/* check if shm_destroy() is tearing down shp */
+		if (shm_file == NULL) {
+			err = -EIDRM;
+			goto out_unlock0;
+		}
+
 		if (is_file_hugepages(shm_file))
 			goto out_unlock0;
 
@@ -1101,6 +1114,14 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr,
 		goto out_unlock;
 
 	ipc_lock_object(&shp->shm_perm);
+
+	/* check if shm_destroy() is tearing down shp */
+	if (shp->shm_file == NULL) {
+		ipc_unlock_object(&shp->shm_perm);
+		err = -EIDRM;
+		goto out_unlock;
+	}
+
 	path = shp->shm_file->f_path;
 	path_get(&path);
 	shp->shm_nattch++;
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 7d57af21f49..dee6cf4e6d3 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -476,40 +476,6 @@ static int vma_has_reserves(struct vm_area_struct *vma, long chg)
 	return 0;
 }
 
-static void copy_gigantic_page(struct page *dst, struct page *src)
-{
-	int i;
-	struct hstate *h = page_hstate(src);
-	struct page *dst_base = dst;
-	struct page *src_base = src;
-
-	for (i = 0; i < pages_per_huge_page(h); ) {
-		cond_resched();
-		copy_highpage(dst, src);
-
-		i++;
-		dst = mem_map_next(dst, dst_base, i);
-		src = mem_map_next(src, src_base, i);
-	}
-}
-
-void copy_huge_page(struct page *dst, struct page *src)
-{
-	int i;
-	struct hstate *h = page_hstate(src);
-
-	if (unlikely(pages_per_huge_page(h) > MAX_ORDER_NR_PAGES)) {
-		copy_gigantic_page(dst, src);
-		return;
-	}
-
-	might_sleep();
-	for (i = 0; i < pages_per_huge_page(h); i++) {
-		cond_resched();
-		copy_highpage(dst + i, src + i);
-	}
-}
-
 static void enqueue_huge_page(struct hstate *h, struct page *page)
 {
 	int nid = page_to_nid(page);
@@ -736,6 +702,23 @@ int PageHuge(struct page *page)
 }
 EXPORT_SYMBOL_GPL(PageHuge);
 
+/*
+ * PageHeadHuge() only returns true for hugetlbfs head page, but not for
+ * normal or transparent huge pages.
+ */
+int PageHeadHuge(struct page *page_head)
+{
+	compound_page_dtor *dtor;
+
+	if (!PageHead(page_head))
+		return 0;
+
+	dtor = get_compound_page_dtor(page_head);
+
+	return dtor == free_huge_page;
+}
+EXPORT_SYMBOL_GPL(PageHeadHuge);
+
 pgoff_t __basepage_index(struct page *page)
 {
 	struct page *page_head = compound_head(page);
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index c4403cdf343..eca4a312912 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2950,7 +2950,7 @@ void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
 		return;
 	}
 
-	p += snprintf(p, maxlen, policy_modes[mode]);
+	p += snprintf(p, maxlen, "%s", policy_modes[mode]);
 
 	if (flags & MPOL_MODE_FLAGS) {
 		p += snprintf(p, buffer + maxlen - p, "=");
diff --git a/mm/migrate.c b/mm/migrate.c
index 316e720a202..bb940045fe8 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -442,6 +442,54 @@ int migrate_huge_page_move_mapping(struct address_space *mapping,
 }
 
 /*
+ * Gigantic pages are so large that we do not guarantee that page++ pointer
+ * arithmetic will work across the entire page.  We need something more
+ * specialized.
+ */
+static void __copy_gigantic_page(struct page *dst, struct page *src,
+				int nr_pages)
+{
+	int i;
+	struct page *dst_base = dst;
+	struct page *src_base = src;
+
+	for (i = 0; i < nr_pages; ) {
+		cond_resched();
+		copy_highpage(dst, src);
+
+		i++;
+		dst = mem_map_next(dst, dst_base, i);
+		src = mem_map_next(src, src_base, i);
+	}
+}
+
+static void copy_huge_page(struct page *dst, struct page *src)
+{
+	int i;
+	int nr_pages;
+
+	if (PageHuge(src)) {
+		/* hugetlbfs page */
+		struct hstate *h = page_hstate(src);
+		nr_pages = pages_per_huge_page(h);
+
+		if (unlikely(nr_pages > MAX_ORDER_NR_PAGES)) {
+			__copy_gigantic_page(dst, src, nr_pages);
+			return;
+		}
+	} else {
+		/* thp page */
+		BUG_ON(!PageTransHuge(src));
+		nr_pages = hpage_nr_pages(src);
+	}
+
+	for (i = 0; i < nr_pages; i++) {
+		cond_resched();
+		copy_highpage(dst + i, src + i);
+	}
+}
+
+/*
  * Copy the page to its new location
  */
 void migrate_page_copy(struct page *newpage, struct page *page)
diff --git a/mm/swap.c b/mm/swap.c
index 7a9f80d451f..84b26aaabd0 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -82,19 +82,6 @@ static void __put_compound_page(struct page *page)
 
 static void put_compound_page(struct page *page)
 {
-	/*
-	 * hugetlbfs pages cannot be split from under us.  If this is a
-	 * hugetlbfs page, check refcount on head page and release the page if
-	 * the refcount becomes zero.
-	 */
-	if (PageHuge(page)) {
-		page = compound_head(page);
-		if (put_page_testzero(page))
-			__put_compound_page(page);
-
-		return;
-	}
-
 	if (unlikely(PageTail(page))) {
 		/* __split_huge_page_refcount can run under us */
 		struct page *page_head = compound_trans_head(page);
@@ -111,14 +98,31 @@ static void put_compound_page(struct page *page)
 			 * still hot on arches that do not support
 			 * this_cpu_cmpxchg_double().
 			 */
-			if (PageSlab(page_head)) {
-				if (PageTail(page)) {
+			if (PageSlab(page_head) || PageHeadHuge(page_head)) {
+				if (likely(PageTail(page))) {
+					/*
+					 * __split_huge_page_refcount
+					 * cannot race here.
+					 */
+					VM_BUG_ON(!PageHead(page_head));
+					atomic_dec(&page->_mapcount);
 					if (put_page_testzero(page_head))
 						VM_BUG_ON(1);
-
-					atomic_dec(&page->_mapcount);
-					goto skip_lock_tail;
+					if (put_page_testzero(page_head))
+						__put_compound_page(page_head);
+					return;
 				} else
+					/*
+					 * __split_huge_page_refcount
+					 * run before us, "page" was a
+					 * THP tail. The split
+					 * page_head has been freed
+					 * and reallocated as slab or
+					 * hugetlbfs page of smaller
+					 * order (only possible if
+					 * reallocated as slab on
+					 * x86).
+					 */
 					goto skip_lock;
 			}
 			/*
@@ -132,8 +136,27 @@ static void put_compound_page(struct page *page)
 				/* __split_huge_page_refcount run before us */
 				compound_unlock_irqrestore(page_head, flags);
 skip_lock:
-				if (put_page_testzero(page_head))
-					__put_single_page(page_head);
+				if (put_page_testzero(page_head)) {
+					/*
+					 * The head page may have been
+					 * freed and reallocated as a
+					 * compound page of smaller
+					 * order and then freed again.
+					 * All we know is that it
+					 * cannot have become: a THP
+					 * page, a compound page of
+					 * higher order, a tail page.
+					 * That is because we still
+					 * hold the refcount of the
+					 * split THP tail and
+					 * page_head was the THP head
+					 * before the split.
+					 */
+					if (PageHead(page_head))
+						__put_compound_page(page_head);
+					else
+						__put_single_page(page_head);
+				}
 out_put_single:
 				if (put_page_testzero(page))
 					__put_single_page(page);
@@ -155,7 +178,6 @@ out_put_single:
 			VM_BUG_ON(atomic_read(&page->_count) != 0);
 			compound_unlock_irqrestore(page_head, flags);
 
-skip_lock_tail:
 			if (put_page_testzero(page_head)) {
 				if (PageHead(page_head))
 					__put_compound_page(page_head);
@@ -198,51 +220,52 @@ bool __get_page_tail(struct page *page)
 	 * proper PT lock that already serializes against
 	 * split_huge_page().
 	 */
+	unsigned long flags;
 	bool got = false;
-	struct page *page_head;
-
-	/*
-	 * If this is a hugetlbfs page it cannot be split under us.  Simply
-	 * increment refcount for the head page.
-	 */
-	if (PageHuge(page)) {
-		page_head = compound_head(page);
-		atomic_inc(&page_head->_count);
-		got = true;
-	} else {
-		unsigned long flags;
+	struct page *page_head = compound_trans_head(page);
 
-		page_head = compound_trans_head(page);
-		if (likely(page != page_head &&
-					get_page_unless_zero(page_head))) {
-
-			/* Ref to put_compound_page() comment. */
-			if (PageSlab(page_head)) {
-				if (likely(PageTail(page))) {
-					__get_page_tail_foll(page, false);
-					return true;
-				} else {
-					put_page(page_head);
-					return false;
-				}
-			}
-
-			/*
-			 * page_head wasn't a dangling pointer but it
-			 * may not be a head page anymore by the time
-			 * we obtain the lock. That is ok as long as it
-			 * can't be freed from under us.
-			 */
-			flags = compound_lock_irqsave(page_head);
-			/* here __split_huge_page_refcount won't run anymore */
+	if (likely(page != page_head && get_page_unless_zero(page_head))) {
+		/* Ref to put_compound_page() comment. */
+		if (PageSlab(page_head) || PageHeadHuge(page_head)) {
 			if (likely(PageTail(page))) {
+				/*
+				 * This is a hugetlbfs page or a slab
+				 * page. __split_huge_page_refcount
+				 * cannot race here.
+				 */
+				VM_BUG_ON(!PageHead(page_head));
 				__get_page_tail_foll(page, false);
-				got = true;
-			}
-			compound_unlock_irqrestore(page_head, flags);
-			if (unlikely(!got))
+				return true;
+			} else {
+				/*
+				 * __split_huge_page_refcount run
+				 * before us, "page" was a THP
+				 * tail. The split page_head has been
+				 * freed and reallocated as slab or
+				 * hugetlbfs page of smaller order
+				 * (only possible if reallocated as
+				 * slab on x86).
+				 */
 				put_page(page_head);
+				return false;
+			}
+		}
+
+		/*
+		 * page_head wasn't a dangling pointer but it
+		 * may not be a head page anymore by the time
+		 * we obtain the lock. That is ok as long as it
+		 * can't be freed from under us.
+		 */
+		flags = compound_lock_irqsave(page_head);
+		/* here __split_huge_page_refcount won't run anymore */
+		if (likely(PageTail(page))) {
+			__get_page_tail_foll(page, false);
+			got = true;
 		}
+		compound_unlock_irqrestore(page_head, flags);
+		if (unlikely(!got))
+			put_page(page_head);
 	}
 	return got;
 }
diff --git a/net/Kconfig b/net/Kconfig
index 0715db64a5c..d334678c0bd 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -224,7 +224,7 @@ source "net/hsr/Kconfig"
 
 config RPS
 	boolean
-	depends on SMP && SYSFS && USE_GENERIC_SMP_HELPERS
+	depends on SMP && SYSFS
 	default y
 
 config RFS_ACCEL
@@ -235,7 +235,7 @@ config RFS_ACCEL
 
 config XPS
 	boolean
-	depends on SMP && USE_GENERIC_SMP_HELPERS
+	depends on SMP
 	default y
 
 config NETPRIO_CGROUP
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 61090e0ff61..9c981003037 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -3289,6 +3289,7 @@ sub process {
 			}
 		}
 		if (!defined $suppress_whiletrailers{$linenr} &&
+		    defined($stat) && defined($cond) &&
 		    $line =~ /\b(?:if|while|for)\s*\(/ && $line !~ /^.\s*#/) {
 			my ($s, $c) = ($stat, $cond);