linux-kernel - [PATCH] x86: add might_sleep() to do_page

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Message-Id: <1233241003.4495.97.camel@laptop>
Date:	Thu, 29 Jan 2009 15:56:43 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Frank Mehnert <Frank.Mehnert@....COM>
Cc:	linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Nick Piggin <npiggin@...e.de>, Ingo Molnar <mingo@...e.hu>
Subject: [PATCH] x86: add might_sleep() to do_page_fault()

VirtualBox calls do_page_fault() from an atomic context but runs into a
might_sleep() way pas this point, cure that.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
---
 arch/x86/mm/fault.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 67e4df5..bb7f946 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -908,6 +908,11 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
 		}
 		down_read(&mm->mmap_sem);
 	}
+	/*
+	 * The above down_read_trylock() might have succeeded in which case
+	 * we'll have missed the might_sleep() from down_read().
+	 */
+	might_sleep();
 
 	vma = find_vma(mm, address);
 	if (unlikely(!vma)) {


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