The patch titled
x86: enable interrupts in user path of page fault
has been removed from the -mm tree. Its filename was
x86-enable-interrupts-in-user-path-of-page-fault.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
Subject: x86: enable interrupts in user path of page fault
From: Steven Rostedt <rostedt@xxxxxxxxxxx>
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 <rostedt@xxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/i386/mm/fault.c | 5 +++++
arch/x86_64/mm/fault.c | 6 ++++++
2 files changed, 11 insertions(+)
diff -puN arch/i386/mm/fault.c~x86-enable-interrupts-in-user-path-of-page-fault arch/i386/mm/fault.c
--- a/arch/i386/mm/fault.c~x86-enable-interrupts-in-user-path-of-page-fault
+++ a/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 -puN arch/x86_64/mm/fault.c~x86-enable-interrupts-in-user-path-of-page-fault arch/x86_64/mm/fault.c
--- a/arch/x86_64/mm/fault.c~x86-enable-interrupts-in-user-path-of-page-fault
+++ a/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;
_
Patches currently in -mm which might be from rostedt@xxxxxxxxxxx are
origin.patch
rt-mutex-fix-stale-return-value.patch
rt-mutex-fix-chain-walk-early-wakeup-bug.patch
pi-futex-fix-exit-races-and-locking-problems.patch
futex-tidy-up-the-code.patch
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