Messages in this thread Patch in this message | | | Date | Sun, 26 May 2019 15:18:31 -0400 | From | Steven Rostedt <> | Subject | [for-next][PATCH 03/16] x86/uaccess: Allow access_ok() in irq context if pagefault_disabled |
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From: Masami Hiramatsu <mhiramat@kernel.org>
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 | 4 +++- include/linux/uaccess.h | 5 ++++- 2 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index c82abd6e4ca3..9c4435307ff8 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -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 diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index 2b70130af585..5a43ef7db492 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -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 -- 2.20.1
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