This is a note to let you know that I've just added the patch titled
x86/fpu: Drop_fpu() should not assume that tsk equals current
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-fpu-drop_fpu-should-not-assume-that-tsk-equals-current.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From f4c3686386393c120710dd34df2a74183ab805fd Mon Sep 17 00:00:00 2001
From: Oleg Nesterov <[email protected]>
Date: Fri, 13 Mar 2015 09:53:10 +0100
Subject: x86/fpu: Drop_fpu() should not assume that tsk equals current
From: Oleg Nesterov <[email protected]>
commit f4c3686386393c120710dd34df2a74183ab805fd upstream.
drop_fpu() does clear_used_math() and usually this is correct
because tsk == current.
However switch_fpu_finish()->restore_fpu_checking() is called before
__switch_to() updates the "current_task" variable. If it fails,
we will wrongly clear the PF_USED_MATH flag of the previous task.
So use clear_stopped_child_used_math() instead.
Signed-off-by: Oleg Nesterov <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Rik van Riel <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Pekka Riikonen <[email protected]>
Cc: Quentin Casasnovas <[email protected]>
Cc: Suresh Siddha <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/x86/include/asm/fpu-internal.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/include/asm/fpu-internal.h
+++ b/arch/x86/include/asm/fpu-internal.h
@@ -370,7 +370,7 @@ static inline void drop_fpu(struct task_
preempt_disable();
tsk->fpu_counter = 0;
__drop_fpu(tsk);
- clear_used_math();
+ clear_stopped_child_used_math(tsk);
preempt_enable();
}
Patches currently in stable-queue which might be from [email protected] are
queue-3.10/x86-fpu-drop_fpu-should-not-assume-that-tsk-equals-current.patch
queue-3.10/x86-fpu-avoid-math_state_restore-without-used_math-in-__restore_xstate_sig.patch
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