diff options
| author | Dima Zavin <dima@android.com> | 2010-04-28 03:57:04 -0700 |
|---|---|---|
| committer | Zhang Jiejing <jiejing.zhang@freescale.com> | 2011-08-30 11:11:30 +0800 |
| commit | 0db94f4ca3eb826ae64331942190dd4e9b1de4b3 (patch) | |
| tree | 851efb43a7ea83db291283c0f1a8f169b726237c | |
| parent | 92b5fd3c7cfb9084b54860daef89f7c4c95126ae (diff) | |
Do not call flush_cache_user_range with mmap_sem held
[ARM] Do not call flush_cache_user_range with mmap_sem held
We can't be holding the mmap_sem while calling flush_cache_user_range
because the flush can fault. If we fault on a user address, the
page fault handler will try to take mmap_sem again. Since both places
acquire the read lock, most of the time it succeeds. However, if another
thread tries to acquire the write lock on the mmap_sem (e.g. mmap) in
between the call to flush_cache_user_range and the fault, the down_read
in do_page_fault will deadlock.
Also, since we really can't be holding the mmap_sem while calling
flush_cache_user_range AND vma is actually unused by the flush itself,
get rid of vma as an argument.
Change-Id: If55409bde41ad1060fa4fe7cbd4ac530d4d9a106
Signed-off-by: Dima Zavin <dima@android.com>
| -rw-r--r-- | arch/arm/include/asm/cacheflush.h | 2 | ||||
| -rw-r--r-- | arch/arm/kernel/traps.c | 4 |
2 files changed, 4 insertions, 2 deletions
diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h index d3730f0f4b50..8c885b6f97f8 100644 --- a/arch/arm/include/asm/cacheflush.h +++ b/arch/arm/include/asm/cacheflush.h @@ -336,7 +336,7 @@ extern void flush_cache_page(struct vm_area_struct *vma, unsigned long user_addr * Harvard caches are synchronised for the user space address range. * This is used for the ARM private sys_cacheflush system call. */ -#define flush_cache_user_range(vma,start,end) \ +#define flush_cache_user_range(start,end) \ __cpuc_coherent_user_range((start) & PAGE_MASK, PAGE_ALIGN(end)) /* diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c index 1621e5327b2a..2455fd36e82c 100644 --- a/arch/arm/kernel/traps.c +++ b/arch/arm/kernel/traps.c @@ -453,7 +453,9 @@ do_cache_op(unsigned long start, unsigned long end, int flags) if (end > vma->vm_end) end = vma->vm_end; - flush_cache_user_range(vma, start, end); + up_read(&mm->mmap_sem); + flush_cache_user_range(start, end); + return; } up_read(&mm->mmap_sem); } |