linux-kernel - Re: [RFC/PATCH] mm/futex: Fix futex writes on archs with SW tracking of dirty & young

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Message-ID: <1311761831.24752.413.camel@twins>
Date:	Wed, 27 Jul 2011 12:17:11 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	David Howells <dhowells@...hat.com>
Cc:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Mike Frysinger <vapier.adi@...il.com>,
	Shan Hai <haishan.bai@...il.com>, paulus@...ba.org,
	tglx@...utronix.de, walken@...gle.com, cmetcalf@...era.com,
	tony.luck@...el.com, akpm@...ux-foundation.org,
	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	uclinux-dist-devel@...ckfin.uclinux.org
Subject: Re: [RFC/PATCH] mm/futex: Fix futex writes on archs with SW
 tracking of dirty & young

On Wed, 2011-07-27 at 11:09 +0100, David Howells wrote:
> Can you inline this for the NOMMU case please?

---
Subject: mm: Fix fixup_user_fault() for MMU=n 

In commit 2efaca927 ("mm/futex: fix futex writes on archs with SW
tracking of dirty & young") we forgot about MMU=n. This patch fixes
that.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
---
Index: linux-2.6/include/linux/mm.h
===================================================================
--- linux-2.6.orig/include/linux/mm.h
+++ linux-2.6/include/linux/mm.h
@@ -962,6 +962,8 @@ int invalidate_inode_page(struct page *p
 #ifdef CONFIG_MMU
 extern int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 			unsigned long address, unsigned int flags);
+extern int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
+			    unsigned long address, unsigned int fault_flags);
 #else
 static inline int handle_mm_fault(struct mm_struct *mm,
 			struct vm_area_struct *vma, unsigned long address,
@@ -971,6 +973,14 @@ static inline int handle_mm_fault(struct
 	BUG();
 	return VM_FAULT_SIGBUS;
 }
+static inline int fixup_user_fault(struct task_struct *tsk, 
+		struct mm_struct *mm, unsigned long address,
+		unsigned int fault_flags)
+{
+	/* should never happen if there's no MMU */
+	BUG();
+	return -EFAULT;
+}
 #endif
 
 extern int make_pages_present(unsigned long addr, unsigned long end);
@@ -988,8 +998,6 @@ int get_user_pages(struct task_struct *t
 int get_user_pages_fast(unsigned long start, int nr_pages, int write,
 			struct page **pages);
 struct page *get_dump_page(unsigned long addr);
-extern int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
-			    unsigned long address, unsigned int fault_flags);
 
 extern int try_to_release_page(struct page * page, gfp_t gfp_mask);
 extern void do_invalidatepage(struct page *page, unsigned long offset);

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