[PATCH v1 03/15] uaccess: clarify that uaccess may only sleep if pagefaults are enabled

From: David Hildenbrand
Date: Mon May 11 2015 - 11:57:08 EST

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In general, non-atomic variants of user access functions must not sleep
if pagefaults are disabled.

Let's update all relevant comments in uaccess code. This also reflects
the might_sleep() checks in might_fault().

Signed-off-by: David Hildenbrand <dahi@xxxxxxxxxxxxxxxxxx>
---
arch/avr32/include/asm/uaccess.h | 12 ++++++----
arch/hexagon/include/asm/uaccess.h | 3 ++-
arch/m32r/include/asm/uaccess.h | 30 +++++++++++++++--------
arch/microblaze/include/asm/uaccess.h | 6 +++--
arch/mips/include/asm/uaccess.h | 45 +++++++++++++++++++++++------------
arch/s390/include/asm/uaccess.h | 15 ++++++++----
arch/score/include/asm/uaccess.h | 15 ++++++++----
arch/tile/include/asm/uaccess.h | 18 +++++++++-----
arch/x86/include/asm/uaccess.h | 15 ++++++++----
arch/x86/include/asm/uaccess_32.h | 6 +++--
arch/x86/lib/usercopy_32.c | 6 +++--
lib/strnlen_user.c | 6 +++--
12 files changed, 118 insertions(+), 59 deletions(-)

diff --git a/arch/avr32/include/asm/uaccess.h b/arch/avr32/include/asm/uaccess.h
index a46f7cf..68cf638 100644
--- a/arch/avr32/include/asm/uaccess.h
+++ b/arch/avr32/include/asm/uaccess.h
@@ -97,7 +97,8 @@ static inline __kernel_size_t __copy_from_user(void *to,
* @x: Value to copy to user space.
* @ptr: Destination address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple value from kernel space to user
* space. It supports simple types like char and int, but not larger
@@ -116,7 +117,8 @@ static inline __kernel_size_t __copy_from_user(void *to,
* @x: Variable to store result.
* @ptr: Source address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple variable from user space to kernel
* space. It supports simple types like char and int, but not larger
@@ -136,7 +138,8 @@ static inline __kernel_size_t __copy_from_user(void *to,
* @x: Value to copy to user space.
* @ptr: Destination address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple value from kernel space to user
* space. It supports simple types like char and int, but not larger
@@ -158,7 +161,8 @@ static inline __kernel_size_t __copy_from_user(void *to,
* @x: Variable to store result.
* @ptr: Source address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple variable from user space to kernel
* space. It supports simple types like char and int, but not larger
diff --git a/arch/hexagon/include/asm/uaccess.h b/arch/hexagon/include/asm/uaccess.h
index e4127e4..f000a38 100644
--- a/arch/hexagon/include/asm/uaccess.h
+++ b/arch/hexagon/include/asm/uaccess.h
@@ -36,7 +36,8 @@
* @addr: User space pointer to start of block to check
* @size: Size of block to check
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Checks if a pointer to a block of memory in user space is valid.
*
diff --git a/arch/m32r/include/asm/uaccess.h b/arch/m32r/include/asm/uaccess.h
index 71adff2..cac7014 100644
--- a/arch/m32r/include/asm/uaccess.h
+++ b/arch/m32r/include/asm/uaccess.h
@@ -91,7 +91,8 @@ static inline void set_fs(mm_segment_t s)
* @addr: User space pointer to start of block to check
* @size: Size of block to check
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Checks if a pointer to a block of memory in user space is valid.
*
@@ -155,7 +156,8 @@ extern int fixup_exception(struct pt_regs *regs);
* @x: Variable to store result.
* @ptr: Source address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple variable from user space to kernel
* space. It supports simple types like char and int, but not larger
@@ -175,7 +177,8 @@ extern int fixup_exception(struct pt_regs *regs);
* @x: Value to copy to user space.
* @ptr: Destination address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple value from kernel space to user
* space. It supports simple types like char and int, but not larger
@@ -194,7 +197,8 @@ extern int fixup_exception(struct pt_regs *regs);
* @x: Variable to store result.
* @ptr: Source address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple variable from user space to kernel
* space. It supports simple types like char and int, but not larger
@@ -274,7 +278,8 @@ do { \
* @x: Value to copy to user space.
* @ptr: Destination address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple value from kernel space to user
* space. It supports simple types like char and int, but not larger
@@ -568,7 +573,8 @@ unsigned long __generic_copy_from_user(void *, const void __user *, unsigned lon
* @from: Source address, in kernel space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from kernel space to user space. Caller must check
* the specified block with access_ok() before calling this function.
@@ -588,7 +594,8 @@ unsigned long __generic_copy_from_user(void *, const void __user *, unsigned lon
* @from: Source address, in kernel space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from kernel space to user space.
*
@@ -606,7 +613,8 @@ unsigned long __generic_copy_from_user(void *, const void __user *, unsigned lon
* @from: Source address, in user space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from user space to kernel space. Caller must check
* the specified block with access_ok() before calling this function.
@@ -626,7 +634,8 @@ unsigned long __generic_copy_from_user(void *, const void __user *, unsigned lon
* @from: Source address, in user space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from user space to kernel space.
*
@@ -677,7 +686,8 @@ unsigned long clear_user(void __user *mem, unsigned long len);
* strlen_user: - Get the size of a string in user space.
* @str: The string to measure.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Get the size of a NUL-terminated string in user space.
*
diff --git a/arch/microblaze/include/asm/uaccess.h b/arch/microblaze/include/asm/uaccess.h
index 62942fd..331b0d3 100644
--- a/arch/microblaze/include/asm/uaccess.h
+++ b/arch/microblaze/include/asm/uaccess.h
@@ -178,7 +178,8 @@ extern long __user_bad(void);
* @x: Variable to store result.
* @ptr: Source address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple variable from user space to kernel
* space. It supports simple types like char and int, but not larger
@@ -290,7 +291,8 @@ extern long __user_bad(void);
* @x: Value to copy to user space.
* @ptr: Destination address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple value from kernel space to user
* space. It supports simple types like char and int, but not larger
diff --git a/arch/mips/include/asm/uaccess.h b/arch/mips/include/asm/uaccess.h
index bf8b324..9722357 100644
--- a/arch/mips/include/asm/uaccess.h
+++ b/arch/mips/include/asm/uaccess.h
@@ -103,7 +103,8 @@ extern u64 __ua_limit;
* @addr: User space pointer to start of block to check
* @size: Size of block to check
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Checks if a pointer to a block of memory in user space is valid.
*
@@ -138,7 +139,8 @@ extern u64 __ua_limit;
* @x: Value to copy to user space.
* @ptr: Destination address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple value from kernel space to user
* space. It supports simple types like char and int, but not larger
@@ -157,7 +159,8 @@ extern u64 __ua_limit;
* @x: Variable to store result.
* @ptr: Source address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple variable from user space to kernel
* space. It supports simple types like char and int, but not larger
@@ -177,7 +180,8 @@ extern u64 __ua_limit;
* @x: Value to copy to user space.
* @ptr: Destination address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple value from kernel space to user
* space. It supports simple types like char and int, but not larger
@@ -199,7 +203,8 @@ extern u64 __ua_limit;
* @x: Variable to store result.
* @ptr: Source address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple variable from user space to kernel
* space. It supports simple types like char and int, but not larger
@@ -498,7 +503,8 @@ extern void __put_user_unknown(void);
* @x: Value to copy to user space.
* @ptr: Destination address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple value from kernel space to user
* space. It supports simple types like char and int, but not larger
@@ -517,7 +523,8 @@ extern void __put_user_unknown(void);
* @x: Variable to store result.
* @ptr: Source address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple variable from user space to kernel
* space. It supports simple types like char and int, but not larger
@@ -537,7 +544,8 @@ extern void __put_user_unknown(void);
* @x: Value to copy to user space.
* @ptr: Destination address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple value from kernel space to user
* space. It supports simple types like char and int, but not larger
@@ -559,7 +567,8 @@ extern void __put_user_unknown(void);
* @x: Variable to store result.
* @ptr: Source address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple variable from user space to kernel
* space. It supports simple types like char and int, but not larger
@@ -815,7 +824,8 @@ extern size_t __copy_user(void *__to, const void *__from, size_t __n);
* @from: Source address, in kernel space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from kernel space to user space. Caller must check
* the specified block with access_ok() before calling this function.
@@ -888,7 +898,8 @@ extern size_t __copy_user_inatomic(void *__to, const void *__from, size_t __n);
* @from: Source address, in kernel space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from kernel space to user space.
*
@@ -1075,7 +1086,8 @@ extern size_t __copy_in_user_eva(void *__to, const void *__from, size_t __n);
* @from: Source address, in user space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from user space to kernel space. Caller must check
* the specified block with access_ok() before calling this function.
@@ -1107,7 +1119,8 @@ extern size_t __copy_in_user_eva(void *__to, const void *__from, size_t __n);
* @from: Source address, in user space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from user space to kernel space.
*
@@ -1329,7 +1342,8 @@ strncpy_from_user(char *__to, const char __user *__from, long __len)
* strlen_user: - Get the size of a string in user space.
* @str: The string to measure.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Get the size of a NUL-terminated string in user space.
*
@@ -1398,7 +1412,8 @@ static inline long __strnlen_user(const char __user *s, long n)
* strnlen_user: - Get the size of a string in user space.
* @str: The string to measure.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Get the size of a NUL-terminated string in user space.
*
diff --git a/arch/s390/include/asm/uaccess.h b/arch/s390/include/asm/uaccess.h
index d64a7a6..9dd4cc4 100644
--- a/arch/s390/include/asm/uaccess.h
+++ b/arch/s390/include/asm/uaccess.h
@@ -98,7 +98,8 @@ static inline unsigned long extable_fixup(const struct exception_table_entry *x)
* @from: Source address, in user space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from user space to kernel space. Caller must check
* the specified block with access_ok() before calling this function.
@@ -118,7 +119,8 @@ unsigned long __must_check __copy_from_user(void *to, const void __user *from,
* @from: Source address, in kernel space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from kernel space to user space. Caller must check
* the specified block with access_ok() before calling this function.
@@ -264,7 +266,8 @@ int __get_user_bad(void) __attribute__((noreturn));
* @from: Source address, in kernel space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from kernel space to user space.
*
@@ -290,7 +293,8 @@ __compiletime_warning("copy_from_user() buffer size is not provably correct")
* @from: Source address, in user space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from user space to kernel space.
*
@@ -348,7 +352,8 @@ static inline unsigned long strnlen_user(const char __user *src, unsigned long n
* strlen_user: - Get the size of a string in user space.
* @str: The string to measure.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Get the size of a NUL-terminated string in user space.
*
diff --git a/arch/score/include/asm/uaccess.h b/arch/score/include/asm/uaccess.h
index ab66ddd..20a3591 100644
--- a/arch/score/include/asm/uaccess.h
+++ b/arch/score/include/asm/uaccess.h
@@ -36,7 +36,8 @@
* @addr: User space pointer to start of block to check
* @size: Size of block to check
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Checks if a pointer to a block of memory in user space is valid.
*
@@ -61,7 +62,8 @@
* @x: Value to copy to user space.
* @ptr: Destination address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple value from kernel space to user
* space. It supports simple types like char and int, but not larger
@@ -79,7 +81,8 @@
* @x: Variable to store result.
* @ptr: Source address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple variable from user space to kernel
* space. It supports simple types like char and int, but not larger
@@ -98,7 +101,8 @@
* @x: Value to copy to user space.
* @ptr: Destination address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple value from kernel space to user
* space. It supports simple types like char and int, but not larger
@@ -119,7 +123,8 @@
* @x: Variable to store result.
* @ptr: Source address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple variable from user space to kernel
* space. It supports simple types like char and int, but not larger
diff --git a/arch/tile/include/asm/uaccess.h b/arch/tile/include/asm/uaccess.h
index d598c11..0a9c4265 100644
--- a/arch/tile/include/asm/uaccess.h
+++ b/arch/tile/include/asm/uaccess.h
@@ -85,7 +85,8 @@ int __range_ok(unsigned long addr, unsigned long size);
* @addr: User space pointer to start of block to check
* @size: Size of block to check
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Checks if a pointer to a block of memory in user space is valid.
*
@@ -199,7 +200,8 @@ extern int __get_user_bad(void)
* @x: Variable to store result.
* @ptr: Source address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple variable from user space to kernel
* space. It supports simple types like char and int, but not larger
@@ -281,7 +283,8 @@ extern int __put_user_bad(void)
* @x: Value to copy to user space.
* @ptr: Destination address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple value from kernel space to user
* space. It supports simple types like char and int, but not larger
@@ -337,7 +340,8 @@ extern int __put_user_bad(void)
* @from: Source address, in kernel space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from kernel space to user space. Caller must check
* the specified block with access_ok() before calling this function.
@@ -373,7 +377,8 @@ copy_to_user(void __user *to, const void *from, unsigned long n)
* @from: Source address, in user space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from user space to kernel space. Caller must check
* the specified block with access_ok() before calling this function.
@@ -444,7 +449,8 @@ static inline unsigned long __must_check copy_from_user(void *to,
* @from: Source address, in user space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from user space to user space. Caller must check
* the specified blocks with access_ok() before calling this function.
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index ace9dec..a8df874 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -74,7 +74,8 @@ static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, un
* @addr: User space pointer to start of block to check
* @size: Size of block to check
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Checks if a pointer to a block of memory in user space is valid.
*
@@ -145,7 +146,8 @@ __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
* @x: Variable to store result.
* @ptr: Source address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple variable from user space to kernel
* space. It supports simple types like char and int, but not larger
@@ -240,7 +242,8 @@ extern void __put_user_8(void);
* @x: Value to copy to user space.
* @ptr: Destination address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple value from kernel space to user
* space. It supports simple types like char and int, but not larger
@@ -455,7 +458,8 @@ struct __large_struct { unsigned long buf[100]; };
* @x: Variable to store result.
* @ptr: Source address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple variable from user space to kernel
* space. It supports simple types like char and int, but not larger
@@ -479,7 +483,8 @@ struct __large_struct { unsigned long buf[100]; };
* @x: Value to copy to user space.
* @ptr: Destination address, in user space.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* This macro copies a single simple value from kernel space to user
* space. It supports simple types like char and int, but not larger
diff --git a/arch/x86/include/asm/uaccess_32.h b/arch/x86/include/asm/uaccess_32.h
index 0ed5504..f5dcb52 100644
--- a/arch/x86/include/asm/uaccess_32.h
+++ b/arch/x86/include/asm/uaccess_32.h
@@ -74,7 +74,8 @@ __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
* @from: Source address, in kernel space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from kernel space to user space. Caller must check
* the specified block with access_ok() before calling this function.
@@ -121,7 +122,8 @@ __copy_from_user_inatomic(void *to, const void __user *from, unsigned long n)
* @from: Source address, in user space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from user space to kernel space. Caller must check
* the specified block with access_ok() before calling this function.
diff --git a/arch/x86/lib/usercopy_32.c b/arch/x86/lib/usercopy_32.c
index e2f5e21..91d93b9 100644
--- a/arch/x86/lib/usercopy_32.c
+++ b/arch/x86/lib/usercopy_32.c
@@ -647,7 +647,8 @@ EXPORT_SYMBOL(__copy_from_user_ll_nocache_nozero);
* @from: Source address, in kernel space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from kernel space to user space.
*
@@ -668,7 +669,8 @@ EXPORT_SYMBOL(_copy_to_user);
* @from: Source address, in user space.
* @n: Number of bytes to copy.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Copy data from user space to kernel space.
*
diff --git a/lib/strnlen_user.c b/lib/strnlen_user.c
index a28df52..36c15a2 100644
--- a/lib/strnlen_user.c
+++ b/lib/strnlen_user.c
@@ -84,7 +84,8 @@ static inline long do_strnlen_user(const char __user *src, unsigned long count,
* @str: The string to measure.
* @count: Maximum count (including NUL character)
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Get the size of a NUL-terminated string in user space.
*
@@ -113,7 +114,8 @@ EXPORT_SYMBOL(strnlen_user);
* strlen_user: - Get the size of a user string INCLUDING final NUL.
* @str: The string to measure.
*
- * Context: User context only. This function may sleep.
+ * Context: User context only. This function may sleep if pagefaults are
+ * enabled.
*
* Get the size of a NUL-terminated string in user space.
*
--
2.1.4

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