Commit 20aa7b21 authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds
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[PATCH] probe_kernel_address() needs to do set_fs()

probe_kernel_address() purports to be generic, only it forgot to select
KERNEL_DS, so it presently won't work right on all architectures.

Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent c140e110
......@@ -65,14 +65,22 @@ static inline unsigned long __copy_from_user_nocache(void *to,
* do_page_fault() doesn't attempt to take mmap_sem. This makes
* probe_kernel_address() suitable for use within regions where the caller
* already holds mmap_sem, or other locks which nest inside mmap_sem.
* This must be a macro because __get_user() needs to know the types of the
* args.
* We don't include enough header files to be able to do the set_fs(). We
* require that the probe_kernel_address() caller will do that.
#define probe_kernel_address(addr, retval) \
({ \
long ret; \
mm_segment_t old_fs = get_fs(); \
set_fs(KERNEL_DS); \
pagefault_disable(); \
ret = __get_user(retval, addr); \
pagefault_enable(); \
set_fs(old_fs); \
ret; \
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