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x86/uaccess: Allow access_ok() in irq context if pagefault_disabled 

WARN_ON_IN_IRQ() assumes that the access_ok() and following
user memory access can sleep. But this assumption is not
always correct; when the pagefault is disabled, following
memory access will just returns -EFAULT and never sleep.

Add pagefault_disabled() check in WARN_ON_ONCE() so that
it can ignore the case we call it with disabling pagefault.
For this purpose, this modified pagefault_disabled() as
an inline function.

Link: http://lkml.kernel.org/r/155789868664.26965.7932665824135793317.stgit@devnote2

Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
alistair/sunxi64-5.4-dsi
Masami Hiramatsu 2019-05-15 14:38:06 +09:00 committed by Steven Rostedt (VMware)
parent 0c9f237979
commit 2d8d8fac3b
2 changed files with 7 additions and 2 deletions
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4
arch/x86/include/asm/uaccess.h
View File

@ -66,7 +66,9 @@ static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, un
})
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
# define WARN_ON_IN_IRQ() WARN_ON_ONCE(!in_task())
static inline bool pagefault_disabled(void);
# define WARN_ON_IN_IRQ() \
WARN_ON_ONCE(!in_task() && !pagefault_disabled())
#else
# define WARN_ON_IN_IRQ()
#endif

5
include/linux/uaccess.h
View File

@ -203,7 +203,10 @@ static inline void pagefault_enable(void)
/*
* Is the pagefault handler disabled? If so, user access methods will not sleep.
*/
#define pagefault_disabled() (current->pagefault_disabled != 0)
static inline bool pagefault_disabled(void)
{
return current->pagefault_disabled != 0;
}
/*
* The pagefault handler is in general disabled by pagefault_disable() or