13 files changed, 230 insertions, 262 deletions

diff --git a/kernel/Makefile b/kernel/Makefile
index 0dfeca4..86e3285 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -174,10 +174,8 @@ signing_key.priv signing_key.x509: x509.genkey
 	@echo "###"
 	@echo "### If this takes a long time, you might wish to run rngd in the"
 	@echo "### background to keep the supply of entropy topped up.  It"
-	@echo "### needs to be run as root, and should use a hardware random"
-	@echo "### number generator if one is available, eg:"
-	@echo "###"
-	@echo "###     rngd -r /dev/hwrandom"
+	@echo "### needs to be run as root, and uses a hardware random"
+	@echo "### number generator if one is available."
 	@echo "###"
 	openssl req -new -nodes -utf8 $(sign_key_with_hash) -days 36500 -batch \
 		-x509 -config x509.genkey \
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 13774b3..f24f724 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1962,9 +1962,8 @@ static void cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
 	 * trading it for newcg is protected by cgroup_mutex, we're safe to drop
 	 * it here; it will be freed under RCU.
 	 */
-	put_css_set(oldcg);
-
 	set_bit(CGRP_RELEASABLE, &oldcgrp->flags);
+	put_css_set(oldcg);
 }
 
 /**
@@ -4815,31 +4814,20 @@ static const struct file_operations proc_cgroupstats_operations = {
  *
  * A pointer to the shared css_set was automatically copied in
  * fork.c by dup_task_struct().  However, we ignore that copy, since
- * it was not made under the protection of RCU, cgroup_mutex or
- * threadgroup_change_begin(), so it might no longer be a valid
- * cgroup pointer.  cgroup_attach_task() might have already changed
- * current->cgroups, allowing the previously referenced cgroup
- * group to be removed and freed.
- *
- * Outside the pointer validity we also need to process the css_set
- * inheritance between threadgoup_change_begin() and
- * threadgoup_change_end(), this way there is no leak in any process
- * wide migration performed by cgroup_attach_proc() that could otherwise
- * miss a thread because it is too early or too late in the fork stage.
+ * it was not made under the protection of RCU or cgroup_mutex, so
+ * might no longer be a valid cgroup pointer.  cgroup_attach_task() might
+ * have already changed current->cgroups, allowing the previously
+ * referenced cgroup group to be removed and freed.
  *
  * At the point that cgroup_fork() is called, 'current' is the parent
  * task, and the passed argument 'child' points to the child task.
  */
 void cgroup_fork(struct task_struct *child)
 {
-	/*
-	 * We don't need to task_lock() current because current->cgroups
-	 * can't be changed concurrently here. The parent obviously hasn't
-	 * exited and called cgroup_exit(), and we are synchronized against
-	 * cgroup migration through threadgroup_change_begin().
-	 */
+	task_lock(current);
 	child->cgroups = current->cgroups;
 	get_css_set(child->cgroups);
+	task_unlock(current);
 	INIT_LIST_HEAD(&child->cg_list);
 }
 
@@ -4895,19 +4883,10 @@ void cgroup_post_fork(struct task_struct *child)
 	 */
 	if (use_task_css_set_links) {
 		write_lock(&css_set_lock);
-		if (list_empty(&child->cg_list)) {
-			/*
-			 * It's safe to use child->cgroups without task_lock()
-			 * here because we are protected through
-			 * threadgroup_change_begin() against concurrent
-			 * css_set change in cgroup_task_migrate(). Also
-			 * the task can't exit at that point until
-			 * wake_up_new_task() is called, so we are protected
-			 * against cgroup_exit() setting child->cgroup to
-			 * init_css_set.
-			 */
+		task_lock(child);
+		if (list_empty(&child->cg_list))
 			list_add(&child->cg_list, &child->cgroups->tasks);
-		}
+		task_unlock(child);
 		write_unlock(&css_set_lock);
 	}
 }
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 98256bc..5cc4e7e 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -78,15 +78,23 @@ static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ];
  */
 static atomic_t uprobe_events = ATOMIC_INIT(0);
 
+/* Have a copy of original instruction */
+#define UPROBE_COPY_INSN	0
+/* Dont run handlers when first register/ last unregister in progress*/
+#define UPROBE_RUN_HANDLER	1
+/* Can skip singlestep */
+#define UPROBE_SKIP_SSTEP	2
+
 struct uprobe {
 	struct rb_node		rb_node;	/* node in the rb tree */
 	atomic_t		ref;
 	struct rw_semaphore	consumer_rwsem;
+	struct mutex		copy_mutex;	/* TODO: kill me and UPROBE_COPY_INSN */
 	struct list_head	pending_list;
 	struct uprobe_consumer	*consumers;
 	struct inode		*inode;		/* Also hold a ref to inode */
 	loff_t			offset;
-	int			flags;
+	unsigned long		flags;
 	struct arch_uprobe	arch;
 };
 
@@ -100,17 +108,12 @@ struct uprobe {
  */
 static bool valid_vma(struct vm_area_struct *vma, bool is_register)
 {
-	if (!vma->vm_file)
-		return false;
-
-	if (!is_register)
-		return true;
+	vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_SHARED;
 
-	if ((vma->vm_flags & (VM_HUGETLB|VM_READ|VM_WRITE|VM_EXEC|VM_SHARED))
-				== (VM_READ|VM_EXEC))
-		return true;
+	if (is_register)
+		flags |= VM_WRITE;
 
-	return false;
+	return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC;
 }
 
 static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset)
@@ -193,19 +196,44 @@ bool __weak is_swbp_insn(uprobe_opcode_t *insn)
 	return *insn == UPROBE_SWBP_INSN;
 }
 
+static void copy_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *opcode)
+{
+	void *kaddr = kmap_atomic(page);
+	memcpy(opcode, kaddr + (vaddr & ~PAGE_MASK), UPROBE_SWBP_INSN_SIZE);
+	kunmap_atomic(kaddr);
+}
+
+static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode)
+{
+	uprobe_opcode_t old_opcode;
+	bool is_swbp;
+
+	copy_opcode(page, vaddr, &old_opcode);
+	is_swbp = is_swbp_insn(&old_opcode);
+
+	if (is_swbp_insn(new_opcode)) {
+		if (is_swbp)		/* register: already installed? */
+			return 0;
+	} else {
+		if (!is_swbp)		/* unregister: was it changed by us? */
+			return 0;
+	}
+
+	return 1;
+}
+
 /*
  * NOTE:
  * Expect the breakpoint instruction to be the smallest size instruction for
  * the architecture. If an arch has variable length instruction and the
  * breakpoint instruction is not of the smallest length instruction
- * supported by that architecture then we need to modify read_opcode /
+ * supported by that architecture then we need to modify is_swbp_at_addr and
  * write_opcode accordingly. This would never be a problem for archs that
  * have fixed length instructions.
  */
 
 /*
  * write_opcode - write the opcode at a given virtual address.
- * @auprobe: arch breakpointing information.
  * @mm: the probed process address space.
  * @vaddr: the virtual address to store the opcode.
  * @opcode: opcode to be written at @vaddr.
@@ -216,8 +244,8 @@ bool __weak is_swbp_insn(uprobe_opcode_t *insn)
  * For mm @mm, write the opcode at @vaddr.
  * Return 0 (success) or a negative errno.
  */
-static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
-			unsigned long vaddr, uprobe_opcode_t opcode)
+static int write_opcode(struct mm_struct *mm, unsigned long vaddr,
+			uprobe_opcode_t opcode)
 {
 	struct page *old_page, *new_page;
 	void *vaddr_old, *vaddr_new;
@@ -226,10 +254,14 @@ static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
 
 retry:
 	/* Read the page with vaddr into memory */
-	ret = get_user_pages(NULL, mm, vaddr, 1, 0, 0, &old_page, &vma);
+	ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma);
 	if (ret <= 0)
 		return ret;
 
+	ret = verify_opcode(old_page, vaddr, &opcode);
+	if (ret <= 0)
+		goto put_old;
+
 	ret = -ENOMEM;
 	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
 	if (!new_page)
@@ -264,63 +296,6 @@ put_old:
 }
 
 /**
- * read_opcode - read the opcode at a given virtual address.
- * @mm: the probed process address space.
- * @vaddr: the virtual address to read the opcode.
- * @opcode: location to store the read opcode.
- *
- * Called with mm->mmap_sem held (for read and with a reference to
- * mm.
- *
- * For mm @mm, read the opcode at @vaddr and store it in @opcode.
- * Return 0 (success) or a negative errno.
- */
-static int read_opcode(struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t *opcode)
-{
-	struct page *page;
-	void *vaddr_new;
-	int ret;
-
-	ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL);
-	if (ret <= 0)
-		return ret;
-
-	vaddr_new = kmap_atomic(page);
-	vaddr &= ~PAGE_MASK;
-	memcpy(opcode, vaddr_new + vaddr, UPROBE_SWBP_INSN_SIZE);
-	kunmap_atomic(vaddr_new);
-
-	put_page(page);
-
-	return 0;
-}
-
-static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr)
-{
-	uprobe_opcode_t opcode;
-	int result;
-
-	if (current->mm == mm) {
-		pagefault_disable();
-		result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr,
-								sizeof(opcode));
-		pagefault_enable();
-
-		if (likely(result == 0))
-			goto out;
-	}
-
-	result = read_opcode(mm, vaddr, &opcode);
-	if (result)
-		return result;
-out:
-	if (is_swbp_insn(&opcode))
-		return 1;
-
-	return 0;
-}
-
-/**
  * set_swbp - store breakpoint at a given address.
  * @auprobe: arch specific probepoint information.
  * @mm: the probed process address space.
@@ -331,18 +306,7 @@ out:
  */
 int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr)
 {
-	int result;
-	/*
-	 * See the comment near uprobes_hash().
-	 */
-	result = is_swbp_at_addr(mm, vaddr);
-	if (result == 1)
-		return 0;
-
-	if (result)
-		return result;
-
-	return write_opcode(auprobe, mm, vaddr, UPROBE_SWBP_INSN);
+	return write_opcode(mm, vaddr, UPROBE_SWBP_INSN);
 }
 
 /**
@@ -357,16 +321,7 @@ int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned
 int __weak
 set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr)
 {
-	int result;
-
-	result = is_swbp_at_addr(mm, vaddr);
-	if (!result)
-		return -EINVAL;
-
-	if (result != 1)
-		return result;
-
-	return write_opcode(auprobe, mm, vaddr, *(uprobe_opcode_t *)auprobe->insn);
+	return write_opcode(mm, vaddr, *(uprobe_opcode_t *)auprobe->insn);
 }
 
 static int match_uprobe(struct uprobe *l, struct uprobe *r)
@@ -473,7 +428,7 @@ static struct uprobe *insert_uprobe(struct uprobe *uprobe)
 	spin_unlock(&uprobes_treelock);
 
 	/* For now assume that the instruction need not be single-stepped */
-	uprobe->flags |= UPROBE_SKIP_SSTEP;
+	__set_bit(UPROBE_SKIP_SSTEP, &uprobe->flags);
 
 	return u;
 }
@@ -495,6 +450,7 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset)
 	uprobe->inode = igrab(inode);
 	uprobe->offset = offset;
 	init_rwsem(&uprobe->consumer_rwsem);
+	mutex_init(&uprobe->copy_mutex);
 
 	/* add to uprobes_tree, sorted on inode:offset */
 	cur_uprobe = insert_uprobe(uprobe);
@@ -515,7 +471,7 @@ static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs)
 {
 	struct uprobe_consumer *uc;
 
-	if (!(uprobe->flags & UPROBE_RUN_HANDLER))
+	if (!test_bit(UPROBE_RUN_HANDLER, &uprobe->flags))
 		return;
 
 	down_read(&uprobe->consumer_rwsem);
@@ -621,29 +577,43 @@ static int copy_insn(struct uprobe *uprobe, struct file *filp)
 	return __copy_insn(mapping, filp, uprobe->arch.insn, bytes, uprobe->offset);
 }
 
-/*
- * How mm->uprobes_state.count gets updated
- * uprobe_mmap() increments the count if
- * 	- it successfully adds a breakpoint.
- * 	- it cannot add a breakpoint, but sees that there is a underlying
- * 	  breakpoint (via a is_swbp_at_addr()).
- *
- * uprobe_munmap() decrements the count if
- * 	- it sees a underlying breakpoint, (via is_swbp_at_addr)
- * 	  (Subsequent uprobe_unregister wouldnt find the breakpoint
- * 	  unless a uprobe_mmap kicks in, since the old vma would be
- * 	  dropped just after uprobe_munmap.)
- *
- * uprobe_register increments the count if:
- * 	- it successfully adds a breakpoint.
- *
- * uprobe_unregister decrements the count if:
- * 	- it sees a underlying breakpoint and removes successfully.
- * 	  (via is_swbp_at_addr)
- * 	  (Subsequent uprobe_munmap wouldnt find the breakpoint
- * 	  since there is no underlying breakpoint after the
- * 	  breakpoint removal.)
- */
+static int prepare_uprobe(struct uprobe *uprobe, struct file *file,
+				struct mm_struct *mm, unsigned long vaddr)
+{
+	int ret = 0;
+
+	if (test_bit(UPROBE_COPY_INSN, &uprobe->flags))
+		return ret;
+
+	mutex_lock(&uprobe->copy_mutex);
+	if (test_bit(UPROBE_COPY_INSN, &uprobe->flags))
+		goto out;
+
+	ret = copy_insn(uprobe, file);
+	if (ret)
+		goto out;
+
+	ret = -ENOTSUPP;
+	if (is_swbp_insn((uprobe_opcode_t *)uprobe->arch.insn))
+		goto out;
+
+	ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr);
+	if (ret)
+		goto out;
+
+	/* write_opcode() assumes we don't cross page boundary */
+	BUG_ON((uprobe->offset & ~PAGE_MASK) +
+			UPROBE_SWBP_INSN_SIZE > PAGE_SIZE);
+
+	smp_wmb(); /* pairs with rmb() in find_active_uprobe() */
+	set_bit(UPROBE_COPY_INSN, &uprobe->flags);
+
+ out:
+	mutex_unlock(&uprobe->copy_mutex);
+
+	return ret;
+}
+
 static int
 install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
 			struct vm_area_struct *vma, unsigned long vaddr)
@@ -661,24 +631,9 @@ install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
 	if (!uprobe->consumers)
 		return 0;
 
-	if (!(uprobe->flags & UPROBE_COPY_INSN)) {
-		ret = copy_insn(uprobe, vma->vm_file);
-		if (ret)
-			return ret;
-
-		if (is_swbp_insn((uprobe_opcode_t *)uprobe->arch.insn))
-			return -ENOTSUPP;
-
-		ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr);
-		if (ret)
-			return ret;
-
-		/* write_opcode() assumes we don't cross page boundary */
-		BUG_ON((uprobe->offset & ~PAGE_MASK) +
-				UPROBE_SWBP_INSN_SIZE > PAGE_SIZE);
-
-		uprobe->flags |= UPROBE_COPY_INSN;
-	}
+	ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr);
+	if (ret)
+		return ret;
 
 	/*
 	 * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(),
@@ -697,15 +652,15 @@ install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
 	return ret;
 }
 
-static void
+static int
 remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr)
 {
 	/* can happen if uprobe_register() fails */
 	if (!test_bit(MMF_HAS_UPROBES, &mm->flags))
-		return;
+		return 0;
 
 	set_bit(MMF_RECALC_UPROBES, &mm->flags);
-	set_orig_insn(&uprobe->arch, mm, vaddr);
+	return set_orig_insn(&uprobe->arch, mm, vaddr);
 }
 
 /*
@@ -820,7 +775,7 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register)
 		struct mm_struct *mm = info->mm;
 		struct vm_area_struct *vma;
 
-		if (err)
+		if (err && is_register)
 			goto free;
 
 		down_write(&mm->mmap_sem);
@@ -836,7 +791,7 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register)
 		if (is_register)
 			err = install_breakpoint(uprobe, mm, vma, info->vaddr);
 		else
-			remove_breakpoint(uprobe, mm, info->vaddr);
+			err |= remove_breakpoint(uprobe, mm, info->vaddr);
 
  unlock:
 		up_write(&mm->mmap_sem);
@@ -893,13 +848,15 @@ int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *
 	mutex_lock(uprobes_hash(inode));
 	uprobe = alloc_uprobe(inode, offset);
 
-	if (uprobe && !consumer_add(uprobe, uc)) {
+	if (!uprobe) {
+		ret = -ENOMEM;
+	} else if (!consumer_add(uprobe, uc)) {
 		ret = __uprobe_register(uprobe);
 		if (ret) {
 			uprobe->consumers = NULL;
 			__uprobe_unregister(uprobe);
 		} else {
-			uprobe->flags |= UPROBE_RUN_HANDLER;
+			set_bit(UPROBE_RUN_HANDLER, &uprobe->flags);
 		}
 	}
 
@@ -932,7 +889,7 @@ void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consume
 	if (consumer_del(uprobe, uc)) {
 		if (!uprobe->consumers) {
 			__uprobe_unregister(uprobe);
-			uprobe->flags &= ~UPROBE_RUN_HANDLER;
+			clear_bit(UPROBE_RUN_HANDLER, &uprobe->flags);
 		}
 	}
 
@@ -1393,10 +1350,11 @@ bool uprobe_deny_signal(void)
  */
 static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs)
 {
-	if (arch_uprobe_skip_sstep(&uprobe->arch, regs))
-		return true;
-
-	uprobe->flags &= ~UPROBE_SKIP_SSTEP;
+	if (test_bit(UPROBE_SKIP_SSTEP, &uprobe->flags)) {
+		if (arch_uprobe_skip_sstep(&uprobe->arch, regs))
+			return true;
+		clear_bit(UPROBE_SKIP_SSTEP, &uprobe->flags);
+	}
 	return false;
 }
 
@@ -1419,6 +1377,30 @@ static void mmf_recalc_uprobes(struct mm_struct *mm)
 	clear_bit(MMF_HAS_UPROBES, &mm->flags);
 }
 
+static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr)
+{
+	struct page *page;
+	uprobe_opcode_t opcode;
+	int result;
+
+	pagefault_disable();
+	result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr,
+							sizeof(opcode));
+	pagefault_enable();
+
+	if (likely(result == 0))
+		goto out;
+
+	result = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL);
+	if (result < 0)
+		return result;
+
+	copy_opcode(page, vaddr, &opcode);
+	put_page(page);
+ out:
+	return is_swbp_insn(&opcode);
+}
+
 static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp)
 {
 	struct mm_struct *mm = current->mm;
@@ -1489,38 +1471,41 @@ static void handle_swbp(struct pt_regs *regs)
 		}
 		return;
 	}
+	/*
+	 * TODO: move copy_insn/etc into _register and remove this hack.
+	 * After we hit the bp, _unregister + _register can install the
+	 * new and not-yet-analyzed uprobe at the same address, restart.
+	 */
+	smp_rmb(); /* pairs with wmb() in install_breakpoint() */
+	if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags)))
+		goto restart;
 
 	utask = current->utask;
 	if (!utask) {
 		utask = add_utask();
 		/* Cannot allocate; re-execute the instruction. */
 		if (!utask)
-			goto cleanup_ret;
+			goto restart;
 	}
-	utask->active_uprobe = uprobe;
+
 	handler_chain(uprobe, regs);
-	if (uprobe->flags & UPROBE_SKIP_SSTEP && can_skip_sstep(uprobe, regs))
-		goto cleanup_ret;
+	if (can_skip_sstep(uprobe, regs))
+		goto out;
 
-	utask->state = UTASK_SSTEP;
 	if (!pre_ssout(uprobe, regs, bp_vaddr)) {
 		arch_uprobe_enable_step(&uprobe->arch);
+		utask->active_uprobe = uprobe;
+		utask->state = UTASK_SSTEP;
 		return;
 	}
 
-cleanup_ret:
-	if (utask) {
-		utask->active_uprobe = NULL;
-		utask->state = UTASK_RUNNING;
-	}
-	if (!(uprobe->flags & UPROBE_SKIP_SSTEP))
-
-		/*
-		 * cannot singlestep; cannot skip instruction;
-		 * re-execute the instruction.
-		 */
-		instruction_pointer_set(regs, bp_vaddr);
-
+restart:
+	/*
+	 * cannot singlestep; cannot skip instruction;
+	 * re-execute the instruction.
+	 */
+	instruction_pointer_set(regs, bp_vaddr);
+out:
 	put_uprobe(uprobe);
 }
 
@@ -1552,13 +1537,12 @@ static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs)
 }
 
 /*
- * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag.  (and on
- * subsequent probe hits on the thread sets the state to UTASK_BP_HIT) and
- * allows the thread to return from interrupt.
+ * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag and
+ * allows the thread to return from interrupt. After that handle_swbp()
+ * sets utask->active_uprobe.
  *
- * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag and
- * also sets the state to UTASK_SSTEP_ACK and allows the thread to return from
- * interrupt.
+ * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag
+ * and allows the thread to return from interrupt.
  *
  * While returning to userspace, thread notices the TIF_UPROBE flag and calls
  * uprobe_notify_resume().
@@ -1567,11 +1551,13 @@ void uprobe_notify_resume(struct pt_regs *regs)
 {
 	struct uprobe_task *utask;
 
+	clear_thread_flag(TIF_UPROBE);
+
 	utask = current->utask;
-	if (!utask || utask->state == UTASK_BP_HIT)
-		handle_swbp(regs);
-	else
+	if (utask && utask->active_uprobe)
 		handle_singlestep(utask, regs);
+	else
+		handle_swbp(regs);
 }
 
 /*
@@ -1580,17 +1566,10 @@ void uprobe_notify_resume(struct pt_regs *regs)
  */
 int uprobe_pre_sstep_notifier(struct pt_regs *regs)
 {
-	struct uprobe_task *utask;
-
 	if (!current->mm || !test_bit(MMF_HAS_UPROBES, &current->mm->flags))
 		return 0;
 
-	utask = current->utask;
-	if (utask)
-		utask->state = UTASK_BP_HIT;
-
 	set_thread_flag(TIF_UPROBE);
-
 	return 1;
 }
 
diff --git a/kernel/module.c b/kernel/module.c
index 6085f5e..6e48c3a 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2293,12 +2293,17 @@ static void layout_symtab(struct module *mod, struct load_info *info)
 	src = (void *)info->hdr + symsect->sh_offset;
 	nsrc = symsect->sh_size / sizeof(*src);
 
+	/* strtab always starts with a nul, so offset 0 is the empty string. */
+	strtab_size = 1;
+
 	/* Compute total space required for the core symbols' strtab. */
-	for (ndst = i = strtab_size = 1; i < nsrc; ++i, ++src)
-		if (is_core_symbol(src, info->sechdrs, info->hdr->e_shnum)) {
-			strtab_size += strlen(&info->strtab[src->st_name]) + 1;
+	for (ndst = i = 0; i < nsrc; i++) {
+		if (i == 0 ||
+		    is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum)) {
+			strtab_size += strlen(&info->strtab[src[i].st_name])+1;
 			ndst++;
 		}
+	}
 
 	/* Append room for core symbols at end of core part. */
 	info->symoffs = ALIGN(mod->core_size, symsect->sh_addralign ?: 1);
@@ -2332,15 +2337,15 @@ static void add_kallsyms(struct module *mod, const struct load_info *info)
 	mod->core_symtab = dst = mod->module_core + info->symoffs;
 	mod->core_strtab = s = mod->module_core + info->stroffs;
 	src = mod->symtab;
-	*dst = *src;
 	*s++ = 0;
-	for (ndst = i = 1; i < mod->num_symtab; ++i, ++src) {
-		if (!is_core_symbol(src, info->sechdrs, info->hdr->e_shnum))
-			continue;
-
-		dst[ndst] = *src;
-		dst[ndst++].st_name = s - mod->core_strtab;
-		s += strlcpy(s, &mod->strtab[src->st_name], KSYM_NAME_LEN) + 1;
+	for (ndst = i = 0; i < mod->num_symtab; i++) {
+		if (i == 0 ||
+		    is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum)) {
+			dst[ndst] = src[i];
+			dst[ndst++].st_name = s - mod->core_strtab;
+			s += strlcpy(s, &mod->strtab[src[i].st_name],
+				     KSYM_NAME_LEN) + 1;
+		}
 	}
 	mod->core_num_syms = ndst;
 }
diff --git a/kernel/module_signing.c b/kernel/module_signing.c
index d492a23..ea1b1df 100644
--- a/kernel/module_signing.c
+++ b/kernel/module_signing.c
@@ -192,7 +192,7 @@ int mod_verify_sig(const void *mod, unsigned long *_modlen)
 	size_t modlen = *_modlen, sig_len;
 	int ret;
 
-	pr_devel("==>%s(,%lu)\n", __func__, modlen);
+	pr_devel("==>%s(,%zu)\n", __func__, modlen);
 
 	if (modlen <= sizeof(ms))
 		return -EBADMSG;
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index eb00be2..7b07cc0 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -71,12 +71,22 @@ err_alloc:
 	return NULL;
 }
 
+/* MAX_PID_NS_LEVEL is needed for limiting size of 'struct pid' */
+#define MAX_PID_NS_LEVEL 32
+
 static struct pid_namespace *create_pid_namespace(struct pid_namespace *parent_pid_ns)
 {
 	struct pid_namespace *ns;
 	unsigned int level = parent_pid_ns->level + 1;
-	int i, err = -ENOMEM;
+	int i;
+	int err;
+
+	if (level > MAX_PID_NS_LEVEL) {
+		err = -EINVAL;
+		goto out;
+	}
 
+	err = -ENOMEM;
 	ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
 	if (ns == NULL)
 		goto out;
diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c
index 6629bf7..7a925ba 100644
--- a/kernel/time/jiffies.c
+++ b/kernel/time/jiffies.c
@@ -58,7 +58,7 @@ static cycle_t jiffies_read(struct clocksource *cs)
 	return (cycle_t) jiffies;
 }
 
-struct clocksource clocksource_jiffies = {
+static struct clocksource clocksource_jiffies = {
 	.name		= "jiffies",
 	.rating		= 1, /* lowest valid rating*/
 	.read		= jiffies_read,
@@ -67,6 +67,8 @@ struct clocksource clocksource_jiffies = {
 	.shift		= JIFFIES_SHIFT,
 };
 
+__cacheline_aligned_in_smp DEFINE_SEQLOCK(jiffies_lock);
+
 #if (BITS_PER_LONG < 64)
 u64 get_jiffies_64(void)
 {
@@ -74,9 +76,9 @@ u64 get_jiffies_64(void)
 	u64 ret;
 
 	do {
-		seq = read_seqbegin(&xtime_lock);
+		seq = read_seqbegin(&jiffies_lock);
 		ret = jiffies_64;
-	} while (read_seqretry(&xtime_lock, seq));
+	} while (read_seqretry(&jiffies_lock, seq));
 	return ret;
 }
 EXPORT_SYMBOL(get_jiffies_64);
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index da6c9ec..b1600a6 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -63,13 +63,13 @@ int tick_is_oneshot_available(void)
 static void tick_periodic(int cpu)
 {
 	if (tick_do_timer_cpu == cpu) {
-		write_seqlock(&xtime_lock);
+		write_seqlock(&jiffies_lock);
 
 		/* Keep track of the next tick event */
 		tick_next_period = ktime_add(tick_next_period, tick_period);
 
 		do_timer(1);
-		write_sequnlock(&xtime_lock);
+		write_sequnlock(&jiffies_lock);
 	}
 
 	update_process_times(user_mode(get_irq_regs()));
@@ -130,9 +130,9 @@ void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
 		ktime_t next;
 
 		do {
-			seq = read_seqbegin(&xtime_lock);
+			seq = read_seqbegin(&jiffies_lock);
 			next = tick_next_period;
-		} while (read_seqretry(&xtime_lock, seq));
+		} while (read_seqretry(&jiffies_lock, seq));
 
 		clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
 
diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index 4e265b9..cf3e59e 100644
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -141,4 +141,3 @@ static inline int tick_device_is_functional(struct clock_event_device *dev)
 #endif
 
 extern void do_timer(unsigned long ticks);
-extern seqlock_t xtime_lock;
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 77729cc..c96fd6a 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -31,7 +31,7 @@
 static DEFINE_PER_CPU(struct tick_sched, tick_cpu_sched);
 
 /*
- * The time, when the last jiffy update happened. Protected by xtime_lock.
+ * The time, when the last jiffy update happened. Protected by jiffies_lock.
  */
 static ktime_t last_jiffies_update;
 
@@ -49,14 +49,14 @@ static void tick_do_update_jiffies64(ktime_t now)
 	ktime_t delta;
 
 	/*
-	 * Do a quick check without holding xtime_lock:
+	 * Do a quick check without holding jiffies_lock:
 	 */
 	delta = ktime_sub(now, last_jiffies_update);
 	if (delta.tv64 < tick_period.tv64)
 		return;
 
-	/* Reevalute with xtime_lock held */
-	write_seqlock(&xtime_lock);
+	/* Reevalute with jiffies_lock held */
+	write_seqlock(&jiffies_lock);
 
 	delta = ktime_sub(now, last_jiffies_update);
 	if (delta.tv64 >= tick_period.tv64) {
@@ -79,7 +79,7 @@ static void tick_do_update_jiffies64(ktime_t now)
 		/* Keep the tick_next_period variable up to date */
 		tick_next_period = ktime_add(last_jiffies_update, tick_period);
 	}
-	write_sequnlock(&xtime_lock);
+	write_sequnlock(&jiffies_lock);
 }
 
 /*
@@ -89,12 +89,12 @@ static ktime_t tick_init_jiffy_update(void)
 {
 	ktime_t period;
 
-	write_seqlock(&xtime_lock);
+	write_seqlock(&jiffies_lock);
 	/* Did we start the jiffies update yet ? */
 	if (last_jiffies_update.tv64 == 0)
 		last_jiffies_update = tick_next_period;
 	period = last_jiffies_update;
-	write_sequnlock(&xtime_lock);
+	write_sequnlock(&jiffies_lock);
 	return period;
 }
 
@@ -109,7 +109,7 @@ static void tick_sched_do_timer(ktime_t now)
 	 * concurrency: This happens only when the cpu in charge went
 	 * into a long sleep. If two cpus happen to assign themself to
 	 * this duty, then the jiffies update is still serialized by
-	 * xtime_lock.
+	 * jiffies_lock.
 	 */
 	if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE))
 		tick_do_timer_cpu = cpu;
@@ -325,11 +325,11 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
 
 	/* Read jiffies and the time when jiffies were updated last */
 	do {
-		seq = read_seqbegin(&xtime_lock);
+		seq = read_seqbegin(&jiffies_lock);
 		last_update = last_jiffies_update;
 		last_jiffies = jiffies;
 		time_delta = timekeeping_max_deferment();
-	} while (read_seqretry(&xtime_lock, seq));
+	} while (read_seqretry(&jiffies_lock, seq));
 
 	if (rcu_needs_cpu(cpu, &rcu_delta_jiffies) || printk_needs_cpu(cpu) ||
 	    arch_needs_cpu(cpu)) {
@@ -859,7 +859,7 @@ void tick_setup_sched_timer(void)
 	/* Get the next period (per cpu) */
 	hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update());
 
-	/* Offset the tick to avert xtime_lock contention. */
+	/* Offset the tick to avert jiffies_lock contention. */
 	if (sched_skew_tick) {
 		u64 offset = ktime_to_ns(tick_period) >> 1;
 		do_div(offset, num_possible_cpus());
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index e424970..4c7de02 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -25,12 +25,6 @@
 
 static struct timekeeper timekeeper;
 
-/*
- * This read-write spinlock protects us from races in SMP while
- * playing with xtime.
- */
-__cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
-
 /* flag for if timekeeping is suspended */
 int __read_mostly timekeeping_suspended;
 
@@ -1299,9 +1293,7 @@ struct timespec get_monotonic_coarse(void)
 }
 
 /*
- * The 64-bit jiffies value is not atomic - you MUST NOT read it
- * without sampling the sequence number in xtime_lock.
- * jiffies is defined in the linker script...
+ * Must hold jiffies_lock
  */
 void do_timer(unsigned long ticks)
 {
@@ -1389,7 +1381,7 @@ EXPORT_SYMBOL_GPL(ktime_get_monotonic_offset);
  */
 void xtime_update(unsigned long ticks)
 {
-	write_seqlock(&xtime_lock);
+	write_seqlock(&jiffies_lock);
 	do_timer(ticks);
-	write_sequnlock(&xtime_lock);
+	write_sequnlock(&jiffies_lock);
 }
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index b32ed0e..b979426 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1567,6 +1567,10 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size,
 
 		put_online_cpus();
 	} else {
+		/* Make sure this CPU has been intitialized */
+		if (!cpumask_test_cpu(cpu_id, buffer->cpumask))
+			goto out;
+
 		cpu_buffer = buffer->buffers[cpu_id];
 
 		if (nr_pages == cpu_buffer->nr_pages)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index d951daa..042d221 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -2982,7 +2982,7 @@ bool cancel_delayed_work(struct delayed_work *dwork)
 
 	set_work_cpu_and_clear_pending(&dwork->work, work_cpu(&dwork->work));
 	local_irq_restore(flags);
-	return true;
+	return ret;
 }
 EXPORT_SYMBOL(cancel_delayed_work);