Merge branch 'akpm' (patches from Andrew)

Merge more updates from Andrew Morton:

 - most of the rest of MM

 - KASAN updates

 - lib/ updates

 - checkpatch updates

 - some binfmt_elf changes

 - various misc bits

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (115 commits)
  kernel/exit.c: avoid undefined behaviour when calling wait4()
  kernel/signal.c: avoid undefined behaviour in kill_something_info
  binfmt_elf: safely increment argv pointers
  s390: reduce ELF_ET_DYN_BASE
  powerpc: move ELF_ET_DYN_BASE to 4GB / 4MB
  arm64: move ELF_ET_DYN_BASE to 4GB / 4MB
  arm: move ELF_ET_DYN_BASE to 4MB
  binfmt_elf: use ELF_ET_DYN_BASE only for PIE
  fs, epoll: short circuit fetching events if thread has been killed
  checkpatch: improve multi-line alignment test
  checkpatch: improve macro reuse test
  checkpatch: change format of --color argument to --color[=WHEN]
  checkpatch: silence perl 5.26.0 unescaped left brace warnings
  checkpatch: improve tests for multiple line function definitions
  checkpatch: remove false warning for commit reference
  checkpatch: fix stepping through statements with $stat and ctx_statement_block
  checkpatch: [HLP]LIST_HEAD is also declaration
  checkpatch: warn when a MAINTAINERS entry isn't [A-Z]:\t
  checkpatch: improve the unnecessary OOM message test
  lib/bsearch.c: micro-optimize pivot position calculation
  ...

7 files changed, 106 insertions, 75 deletions

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 5075fd5c62c8..879ff9c7ffd0 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -163,8 +163,6 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec,
 	unsigned long p = bprm->p;
 	int argc = bprm->argc;
 	int envc = bprm->envc;
-	elf_addr_t __user *argv;
-	elf_addr_t __user *envp;
 	elf_addr_t __user *sp;
 	elf_addr_t __user *u_platform;
 	elf_addr_t __user *u_base_platform;
@@ -304,38 +302,38 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec,
 	/* Now, let's put argc (and argv, envp if appropriate) on the stack */
 	if (__put_user(argc, sp++))
 		return -EFAULT;
-	argv = sp;
-	envp = argv + argc + 1;
 
-	/* Populate argv and envp */
+	/* Populate list of argv pointers back to argv strings. */
 	p = current->mm->arg_end = current->mm->arg_start;
 	while (argc-- > 0) {
 		size_t len;
-		if (__put_user((elf_addr_t)p, argv++))
+		if (__put_user((elf_addr_t)p, sp++))
 			return -EFAULT;
 		len = strnlen_user((void __user *)p, MAX_ARG_STRLEN);
 		if (!len || len > MAX_ARG_STRLEN)
 			return -EINVAL;
 		p += len;
 	}
-	if (__put_user(0, argv))
+	if (__put_user(0, sp++))
 		return -EFAULT;
-	current->mm->arg_end = current->mm->env_start = p;
+	current->mm->arg_end = p;
+
+	/* Populate list of envp pointers back to envp strings. */
+	current->mm->env_end = current->mm->env_start = p;
 	while (envc-- > 0) {
 		size_t len;
-		if (__put_user((elf_addr_t)p, envp++))
+		if (__put_user((elf_addr_t)p, sp++))
 			return -EFAULT;
 		len = strnlen_user((void __user *)p, MAX_ARG_STRLEN);
 		if (!len || len > MAX_ARG_STRLEN)
 			return -EINVAL;
 		p += len;
 	}
-	if (__put_user(0, envp))
+	if (__put_user(0, sp++))
 		return -EFAULT;
 	current->mm->env_end = p;
 
 	/* Put the elf_info on the stack in the right place.  */
-	sp = (elf_addr_t __user *)envp + 1;
 	if (copy_to_user(sp, elf_info, ei_index * sizeof(elf_addr_t)))
 		return -EFAULT;
 	return 0;
@@ -927,17 +925,60 @@ static int load_elf_binary(struct linux_binprm *bprm)
 		elf_flags = MAP_PRIVATE | MAP_DENYWRITE | MAP_EXECUTABLE;
 
 		vaddr = elf_ppnt->p_vaddr;
+		/*
+		 * If we are loading ET_EXEC or we have already performed
+		 * the ET_DYN load_addr calculations, proceed normally.
+		 */
 		if (loc->elf_ex.e_type == ET_EXEC || load_addr_set) {
 			elf_flags |= MAP_FIXED;
 		} else if (loc->elf_ex.e_type == ET_DYN) {
-			/* Try and get dynamic programs out of the way of the
-			 * default mmap base, as well as whatever program they
-			 * might try to exec.  This is because the brk will
-			 * follow the loader, and is not movable.  */
-			load_bias = ELF_ET_DYN_BASE - vaddr;
-			if (current->flags & PF_RANDOMIZE)
-				load_bias += arch_mmap_rnd();
-			load_bias = ELF_PAGESTART(load_bias);
+			/*
+			 * This logic is run once for the first LOAD Program
+			 * Header for ET_DYN binaries to calculate the
+			 * randomization (load_bias) for all the LOAD
+			 * Program Headers, and to calculate the entire
+			 * size of the ELF mapping (total_size). (Note that
+			 * load_addr_set is set to true later once the
+			 * initial mapping is performed.)
+			 *
+			 * There are effectively two types of ET_DYN
+			 * binaries: programs (i.e. PIE: ET_DYN with INTERP)
+			 * and loaders (ET_DYN without INTERP, since they
+			 * _are_ the ELF interpreter). The loaders must
+			 * be loaded away from programs since the program
+			 * may otherwise collide with the loader (especially
+			 * for ET_EXEC which does not have a randomized
+			 * position). For example to handle invocations of
+			 * "./ld.so someprog" to test out a new version of
+			 * the loader, the subsequent program that the
+			 * loader loads must avoid the loader itself, so
+			 * they cannot share the same load range. Sufficient
+			 * room for the brk must be allocated with the
+			 * loader as well, since brk must be available with
+			 * the loader.
+			 *
+			 * Therefore, programs are loaded offset from
+			 * ELF_ET_DYN_BASE and loaders are loaded into the
+			 * independently randomized mmap region (0 load_bias
+			 * without MAP_FIXED).
+			 */
+			if (elf_interpreter) {
+				load_bias = ELF_ET_DYN_BASE;
+				if (current->flags & PF_RANDOMIZE)
+					load_bias += arch_mmap_rnd();
+				elf_flags |= MAP_FIXED;
+			} else
+				load_bias = 0;
+
+			/*
+			 * Since load_bias is used for all subsequent loading
+			 * calculations, we must lower it by the first vaddr
+			 * so that the remaining calculations based on the
+			 * ELF vaddrs will be correctly offset. The result
+			 * is then page aligned.
+			 */
+			load_bias = ELF_PAGESTART(load_bias - vaddr);
+
 			total_size = total_mapping_size(elf_phdata,
 							loc->elf_ex.e_phnum);
 			if (!total_size) {
diff --git a/fs/buffer.c b/fs/buffer.c
index ea0e05ec2916..5715dac7821f 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1281,44 +1281,31 @@ static inline void check_irqs_on(void)
 }
 
 /*
- * The LRU management algorithm is dopey-but-simple.  Sorry.
+ * Install a buffer_head into this cpu's LRU.  If not already in the LRU, it is
+ * inserted at the front, and the buffer_head at the back if any is evicted.
+ * Or, if already in the LRU it is moved to the front.
  */
 static void bh_lru_install(struct buffer_head *bh)
 {
-	struct buffer_head *evictee = NULL;
+	struct buffer_head *evictee = bh;
+	struct bh_lru *b;
+	int i;
 
 	check_irqs_on();
 	bh_lru_lock();
-	if (__this_cpu_read(bh_lrus.bhs[0]) != bh) {
-		struct buffer_head *bhs[BH_LRU_SIZE];
-		int in;
-		int out = 0;
-
-		get_bh(bh);
-		bhs[out++] = bh;
-		for (in = 0; in < BH_LRU_SIZE; in++) {
-			struct buffer_head *bh2 =
-				__this_cpu_read(bh_lrus.bhs[in]);
 
-			if (bh2 == bh) {
-				__brelse(bh2);
-			} else {
-				if (out >= BH_LRU_SIZE) {
-					BUG_ON(evictee != NULL);
-					evictee = bh2;
-				} else {
-					bhs[out++] = bh2;
-				}
-			}
+	b = this_cpu_ptr(&bh_lrus);
+	for (i = 0; i < BH_LRU_SIZE; i++) {
+		swap(evictee, b->bhs[i]);
+		if (evictee == bh) {
+			bh_lru_unlock();
+			return;
 		}
-		while (out < BH_LRU_SIZE)
-			bhs[out++] = NULL;
-		memcpy(this_cpu_ptr(&bh_lrus.bhs), bhs, sizeof(bhs));
 	}
-	bh_lru_unlock();
 
-	if (evictee)
-		__brelse(evictee);
+	get_bh(bh);
+	bh_lru_unlock();
+	brelse(evictee);
 }
 
 /*
diff --git a/fs/dcache.c b/fs/dcache.c
index 7ece68d0d4db..6c30be668487 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1160,11 +1160,12 @@ void shrink_dcache_sb(struct super_block *sb)
 		LIST_HEAD(dispose);
 
 		freed = list_lru_walk(&sb->s_dentry_lru,
-			dentry_lru_isolate_shrink, &dispose, UINT_MAX);
+			dentry_lru_isolate_shrink, &dispose, 1024);
 
 		this_cpu_sub(nr_dentry_unused, freed);
 		shrink_dentry_list(&dispose);
-	} while (freed > 0);
+		cond_resched();
+	} while (list_lru_count(&sb->s_dentry_lru) > 0);
 }
 EXPORT_SYMBOL(shrink_dcache_sb);
 
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index b1c8e23ddf65..a6d194831ed8 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1748,6 +1748,16 @@ fetch_events:
 			 * to TASK_INTERRUPTIBLE before doing the checks.
 			 */
 			set_current_state(TASK_INTERRUPTIBLE);
+			/*
+			 * Always short-circuit for fatal signals to allow
+			 * threads to make a timely exit without the chance of
+			 * finding more events available and fetching
+			 * repeatedly.
+			 */
+			if (fatal_signal_pending(current)) {
+				res = -EINTR;
+				break;
+			}
 			if (ep_events_available(ep) || timed_out)
 				break;
 			if (signal_pending(current)) {
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index d44f5456eb9b..52388611635e 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -851,6 +851,16 @@ static int hugetlbfs_migrate_page(struct address_space *mapping,
 	return MIGRATEPAGE_SUCCESS;
 }
 
+static int hugetlbfs_error_remove_page(struct address_space *mapping,
+				struct page *page)
+{
+	struct inode *inode = mapping->host;
+
+	remove_huge_page(page);
+	hugetlb_fix_reserve_counts(inode);
+	return 0;
+}
+
 static int hugetlbfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(dentry->d_sb);
@@ -966,6 +976,7 @@ static const struct address_space_operations hugetlbfs_aops = {
 	.write_end	= hugetlbfs_write_end,
 	.set_page_dirty	= hugetlbfs_set_page_dirty,
 	.migratepage    = hugetlbfs_migrate_page,
+	.error_remove_page	= hugetlbfs_error_remove_page,
 };
 
 
diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 9425c0d97262..e3cda0b5968f 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -180,7 +180,6 @@ static int xlate_proc_name(const char *name, struct proc_dir_entry **ret,
 }
 
 static DEFINE_IDA(proc_inum_ida);
-static DEFINE_SPINLOCK(proc_inum_lock); /* protects the above */
 
 #define PROC_DYNAMIC_FIRST 0xF0000000U
 
@@ -190,37 +189,20 @@ static DEFINE_SPINLOCK(proc_inum_lock); /* protects the above */
  */
 int proc_alloc_inum(unsigned int *inum)
 {
-	unsigned int i;
-	int error;
+	int i;
 
-retry:
-	if (!ida_pre_get(&proc_inum_ida, GFP_KERNEL))
-		return -ENOMEM;
+	i = ida_simple_get(&proc_inum_ida, 0, UINT_MAX - PROC_DYNAMIC_FIRST + 1,
+			   GFP_KERNEL);
+	if (i < 0)
+		return i;
 
-	spin_lock_irq(&proc_inum_lock);
-	error = ida_get_new(&proc_inum_ida, &i);
-	spin_unlock_irq(&proc_inum_lock);
-	if (error == -EAGAIN)
-		goto retry;
-	else if (error)
-		return error;
-
-	if (i > UINT_MAX - PROC_DYNAMIC_FIRST) {
-		spin_lock_irq(&proc_inum_lock);
-		ida_remove(&proc_inum_ida, i);
-		spin_unlock_irq(&proc_inum_lock);
-		return -ENOSPC;
-	}
-	*inum = PROC_DYNAMIC_FIRST + i;
+	*inum = PROC_DYNAMIC_FIRST + (unsigned int)i;
 	return 0;
 }
 
 void proc_free_inum(unsigned int inum)
 {
-	unsigned long flags;
-	spin_lock_irqsave(&proc_inum_lock, flags);
-	ida_remove(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
-	spin_unlock_irqrestore(&proc_inum_lock, flags);
+	ida_simple_remove(&proc_inum_ida, inum - PROC_DYNAMIC_FIRST);
 }
 
 /*
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 520802da059c..b836fd61ed87 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -298,7 +298,6 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
 		pgoff = ((loff_t)vma->vm_pgoff) << PAGE_SHIFT;
 	}
 
-	/* We don't show the stack guard page in /proc/maps */
 	start = vma->vm_start;
 	end = vma->vm_end;