x86/uaccess: Allow access_ok() in irq context if pagefault_disabled (2d8d8fac) · Commits · 戴 / test

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>

arch/x86/include/asm/uaccess.h

+3 −1

Original line number	Diff line number	Diff line
		@@ -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

include/linux/uaccess.h

+4 −1

Original line number	Diff line number	Diff line
		@@ -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

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