From 5040573e49cc8f0e016a83544a0e552f2f44c897 Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Wed, 4 Jun 2014 16:07:29 -0700 Subject: arc: call find_vma with the mmap_sem held Performing vma lookups without taking the mm->mmap_sem is asking for trouble. While doing the search, the vma in question can be modified or even removed before returning to the caller. Take the lock (shared) in order to avoid races while iterating through the vmacache and/or rbtree. [akpm@linux-foundation.org: CSE current->active_mm, per Vineet] Signed-off-by: Davidlohr Bueso Acked-by: Vineet Gupta Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds diff --git a/arch/arc/kernel/troubleshoot.c b/arch/arc/kernel/troubleshoot.c index 73a7450..1badf9b 100644 --- a/arch/arc/kernel/troubleshoot.c +++ b/arch/arc/kernel/troubleshoot.c @@ -86,12 +86,13 @@ static void show_faulting_vma(unsigned long address, char *buf) unsigned long ino = 0; dev_t dev = 0; char *nm = buf; + struct mm_struct *active_mm = current->active_mm; /* can't use print_vma_addr() yet as it doesn't check for * non-inclusive vma */ - - vma = find_vma(current->active_mm, address); + down_read(&active_mm->mmap_sem); + vma = find_vma(active_mm, address); /* check against the find_vma( ) behaviour which returns the next VMA * if the container VMA is not found @@ -110,9 +111,10 @@ static void show_faulting_vma(unsigned long address, char *buf) vma->vm_start < TASK_UNMAPPED_BASE ? address : address - vma->vm_start, nm, vma->vm_start, vma->vm_end); - } else { + } else pr_info(" @No matching VMA found\n"); - } + + up_read(&active_mm->mmap_sem); } static void show_ecr_verbose(struct pt_regs *regs) -- cgit v0.10.2