From e5e3c84b70e58fc605635fd340fb8dba3cc59058 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 6 Jun 2007 23:34:04 -0400 Subject: [PATCH] enable interrupts in user path of page fault. This is a minor fix, but what is currently there is essentially wrong. In do_page_fault, if the faulting address from user code happens to be in kernel address space (int *p = (int*)-1; p = 0xbed;) then the do_page_fault handler will jump over the local_irq_enable with the goto bad_area_nosemaphore; But the first line there sees this is user code and goes through the process of sending a signal to send SIGSEGV to the user task. This whole time interrupts are disabled and the task can not be preempted by a higher priority task. This patch always enables interrupts in the user path of the bad_area_nosemaphore. Signed-off-by: Steven Rostedt Signed-off-by: Linus Torvalds --- arch/i386/mm/fault.c | 5 +++++ arch/x86_64/mm/fault.c | 6 ++++++ 2 files changed, 11 insertions(+) diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c index 29d7d61543a1..1ecb3e43b523 100644 --- a/arch/i386/mm/fault.c +++ b/arch/i386/mm/fault.c @@ -458,6 +458,11 @@ bad_area: bad_area_nosemaphore: /* User mode accesses just cause a SIGSEGV */ if (error_code & 4) { + /* + * It's possible to have interrupts off here. + */ + local_irq_enable(); + /* * Valid to do another page fault here because this one came * from user space. diff --git a/arch/x86_64/mm/fault.c b/arch/x86_64/mm/fault.c index bfb62a13d7ee..635e58d443d7 100644 --- a/arch/x86_64/mm/fault.c +++ b/arch/x86_64/mm/fault.c @@ -476,6 +476,12 @@ bad_area: bad_area_nosemaphore: /* User mode accesses just cause a SIGSEGV */ if (error_code & PF_USER) { + + /* + * It's possible to have interrupts off here. + */ + local_irq_enable(); + if (is_prefetch(regs, address, error_code)) return; -- 2.20.1