From: David Hildenbrand <dahi@linux.vnet.ibm.com>
To: linuxppc-dev@lists.ozlabs.org, linux-arch@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: borntraeger@de.ibm.com, heiko.carstens@de.ibm.com,
dahi@linux.vnet.ibm.com, paulus@samba.org,
schwidefsky@de.ibm.com, akpm@linux-foundation.org
Subject: [RFC 2/2] mm, sched: trigger might_sleep() in might_fault() when atomic
Date: Tue, 25 Nov 2014 12:43:26 +0100 [thread overview]
Message-ID: <1416915806-24757-3-git-send-email-dahi@linux.vnet.ibm.com> (raw)
In-Reply-To: <1416915806-24757-1-git-send-email-dahi@linux.vnet.ibm.com>
Commit 662bbcb2747c2422cf98d3d97619509379eee466 disabled in atomic checks
for all user access code (that uses might_fault()).
That change basically disabled CONFIG_DEBUG_ATOMIC_SLEEP for all user access
functions. However, this is a mighty debugging aid that we want.
If user memory is to be accessed while pagefault_disabled() is set, the atomic
variants of copy_(to|from)_user can be used.
This patch reverts commit 662bbcb2747c2422cf98d3d97619509379eee466 taking care
of the !MMU optimization.
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
---
include/linux/kernel.h | 8 ++++++--
mm/memory.c | 11 ++++-------
2 files changed, 10 insertions(+), 9 deletions(-)
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 3d770f55..1d3397c 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -225,9 +225,13 @@ static inline u32 reciprocal_scale(u32 val, u32 ep_ro)
return (u32)(((u64) val * ep_ro) >> 32);
}
-#if defined(CONFIG_MMU) && \
- (defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP))
+#if defined(CONFIG_MMU) && defined(CONFIG_PROVE_LOCKING)
void might_fault(void);
+#elif defined(CONFIG_MMU) && defined(CONFIG_DEBUG_ATOMIC_SLEEP)
+static inline void might_fault(void)
+{
+ __might_sleep(__FILE__, __LINE__, 0);
+}
#else
static inline void might_fault(void) { }
#endif
diff --git a/mm/memory.c b/mm/memory.c
index 3e50383..fe0c815 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3699,7 +3699,7 @@ void print_vma_addr(char *prefix, unsigned long ip)
up_read(&mm->mmap_sem);
}
-#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
+#ifdef CONFIG_PROVE_LOCKING
void might_fault(void)
{
/*
@@ -3711,17 +3711,14 @@ void might_fault(void)
if (segment_eq(get_fs(), KERNEL_DS))
return;
+ __might_sleep(__FILE__, __LINE__, 0);
+
/*
* it would be nicer only to annotate paths which are not under
* pagefault_disable, however that requires a larger audit and
* providing helpers like get_user_atomic.
*/
- if (in_atomic())
- return;
-
- __might_sleep(__FILE__, __LINE__, 0);
-
- if (current->mm)
+ if (!in_atomic() && current->mm)
might_lock_read(¤t->mm->mmap_sem);
}
EXPORT_SYMBOL(might_fault);
--
1.8.5.5
next prev parent reply other threads:[~2014-11-25 11:43 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-25 11:43 [RFC 0/2] Reenable might_sleep() checks for might_fault() when atomic David Hildenbrand
2014-11-25 11:43 ` [RFC 1/2] powerpc/fsl-pci: atomic get_user when pagefault_disabled David Hildenbrand
2015-01-30 5:15 ` [RFC,1/2] " Scott Wood
2015-01-30 7:58 ` David Hildenbrand
2014-11-25 11:43 ` David Hildenbrand [this message]
2014-11-26 7:02 ` [RFC 0/2] Reenable might_sleep() checks for might_fault() when atomic Michael S. Tsirkin
2014-11-26 10:05 ` David Hildenbrand
2014-11-26 15:17 ` Michael S. Tsirkin
2014-11-26 15:23 ` Michael S. Tsirkin
2014-11-26 15:32 ` David Hildenbrand
2014-11-26 15:47 ` Michael S. Tsirkin
2014-11-26 16:02 ` David Hildenbrand
2014-11-26 16:19 ` Michael S. Tsirkin
2014-11-26 16:30 ` Christian Borntraeger
2014-11-26 16:50 ` Michael S. Tsirkin
2014-11-26 16:07 ` Christian Borntraeger
2014-11-26 16:32 ` Michael S. Tsirkin
2014-11-26 16:51 ` Christian Borntraeger
2014-11-26 17:04 ` Michael S. Tsirkin
2014-11-26 17:21 ` Michael S. Tsirkin
2014-11-27 7:09 ` Heiko Carstens
2014-11-27 7:40 ` Michael S. Tsirkin
2014-11-27 8:03 ` David Hildenbrand
2014-11-27 12:04 ` Heiko Carstens
2014-11-27 12:08 ` David Hildenbrand
2014-11-27 15:07 ` Thomas Gleixner
2014-11-27 15:19 ` David Hildenbrand
2014-11-27 15:37 ` David Laight
2014-11-27 15:45 ` David Hildenbrand
2014-11-27 16:27 ` David Laight
2014-11-27 16:49 ` David Hildenbrand
2014-11-27 21:52 ` Thomas Gleixner
2014-11-28 7:34 ` David Hildenbrand
2014-11-26 15:30 ` Christian Borntraeger
2014-11-26 15:37 ` Michael S. Tsirkin
2014-11-26 16:02 ` Christian Borntraeger
2014-11-26 15:22 ` Michael S. Tsirkin
2014-11-27 17:10 ` [PATCH RFC " David Hildenbrand
2014-11-27 17:10 ` [PATCH RFC 1/2] preempt: track pagefault_disable() calls in the preempt counter David Hildenbrand
2014-11-27 17:10 ` [PATCH RFC 2/2] mm, sched: trigger might_sleep() in might_fault() when pagefaults are disabled David Hildenbrand
2014-11-27 17:24 ` Michael S. Tsirkin
2014-11-27 17:32 ` Michael S. Tsirkin
2014-11-27 18:08 ` David Hildenbrand
2014-11-27 18:27 ` Michael S. Tsirkin
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