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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2010-10-27 15:32:58 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-10-27 18:03:05 -0700
commit20273941f2129aa5a432796d98a276ed73d60782 (patch)
tree85da0d951ac10f239f81ad7f69559fdeb692095b /arch
parenta8e23a291852cd7c4fb5ca696dbb93912185ad10 (diff)
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mm: fix race in kunmap_atomic()
Christoph reported a nice splat which illustrated a race in the new stack based kmap_atomic implementation. The problem is that we pop our stack slot before we're completely done resetting its state -- in particular clearing the PTE (sometimes that's CONFIG_DEBUG_HIGHMEM). If an interrupt happens before we actually clear the PTE used for the last slot, that interrupt can reuse the slot in a dirty state, which triggers a BUG in kmap_atomic(). Fix this by introducing kmap_atomic_idx() which reports the current slot index without actually releasing it and use that to find the PTE and delay the _pop() until after we're completely done. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Reported-by: Christoph Hellwig <hch@infradead.org> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/mm/highmem.c3
-rw-r--r--arch/frv/mm/highmem.c3
-rw-r--r--arch/mips/mm/highmem.c3
-rw-r--r--arch/mn10300/include/asm/highmem.h4
-rw-r--r--arch/powerpc/mm/highmem.c4
-rw-r--r--arch/sparc/mm/highmem.c4
-rw-r--r--arch/tile/mm/highmem.c3
-rw-r--r--arch/x86/mm/highmem_32.c3
-rw-r--r--arch/x86/mm/iomap_32.c3
9 files changed, 21 insertions, 9 deletions
diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c
index c00f119babb..c435fd9e1da 100644
--- a/arch/arm/mm/highmem.c
+++ b/arch/arm/mm/highmem.c
@@ -89,7 +89,7 @@ void __kunmap_atomic(void *kvaddr)
int idx, type;
if (kvaddr >= (void *)FIXADDR_START) {
- type = kmap_atomic_idx_pop();
+ type = kmap_atomic_idx();
idx = type + KM_TYPE_NR * smp_processor_id();
if (cache_is_vivt())
@@ -101,6 +101,7 @@ void __kunmap_atomic(void *kvaddr)
#else
(void) idx; /* to kill a warning */
#endif
+ kmap_atomic_idx_pop();
} else if (vaddr >= PKMAP_ADDR(0) && vaddr < PKMAP_ADDR(LAST_PKMAP)) {
/* this address was obtained through kmap_high_get() */
kunmap_high(pte_page(pkmap_page_table[PKMAP_NR(vaddr)]));
diff --git a/arch/frv/mm/highmem.c b/arch/frv/mm/highmem.c
index 61088dcc159..fd7fcd4c2e3 100644
--- a/arch/frv/mm/highmem.c
+++ b/arch/frv/mm/highmem.c
@@ -68,7 +68,7 @@ EXPORT_SYMBOL(__kmap_atomic);
void __kunmap_atomic(void *kvaddr)
{
- int type = kmap_atomic_idx_pop();
+ int type = kmap_atomic_idx();
switch (type) {
case 0: __kunmap_atomic_primary(4, 6); break;
case 1: __kunmap_atomic_primary(5, 7); break;
@@ -83,6 +83,7 @@ void __kunmap_atomic(void *kvaddr)
default:
BUG();
}
+ kmap_atomic_idx_pop();
pagefault_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);
diff --git a/arch/mips/mm/highmem.c b/arch/mips/mm/highmem.c
index 1e69b1fb4b8..3634c7ea06a 100644
--- a/arch/mips/mm/highmem.c
+++ b/arch/mips/mm/highmem.c
@@ -74,7 +74,7 @@ void __kunmap_atomic(void *kvaddr)
return;
}
- type = kmap_atomic_idx_pop();
+ type = kmap_atomic_idx();
#ifdef CONFIG_DEBUG_HIGHMEM
{
int idx = type + KM_TYPE_NR * smp_processor_id();
@@ -89,6 +89,7 @@ void __kunmap_atomic(void *kvaddr)
local_flush_tlb_one(vaddr);
}
#endif
+ kmap_atomic_idx_pop();
pagefault_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);
diff --git a/arch/mn10300/include/asm/highmem.h b/arch/mn10300/include/asm/highmem.h
index f577ba2268c..e2155e68645 100644
--- a/arch/mn10300/include/asm/highmem.h
+++ b/arch/mn10300/include/asm/highmem.h
@@ -101,7 +101,7 @@ static inline void __kunmap_atomic(unsigned long vaddr)
return;
}
- type = kmap_atomic_idx_pop();
+ type = kmap_atomic_idx();
#if HIGHMEM_DEBUG
{
@@ -119,6 +119,8 @@ static inline void __kunmap_atomic(unsigned long vaddr)
__flush_tlb_one(vaddr);
}
#endif
+
+ kmap_atomic_idx_pop();
pagefault_enable();
}
#endif /* __KERNEL__ */
diff --git a/arch/powerpc/mm/highmem.c b/arch/powerpc/mm/highmem.c
index b0848b462bb..e7450bdbe83 100644
--- a/arch/powerpc/mm/highmem.c
+++ b/arch/powerpc/mm/highmem.c
@@ -62,7 +62,7 @@ void __kunmap_atomic(void *kvaddr)
return;
}
- type = kmap_atomic_idx_pop();
+ type = kmap_atomic_idx();
#ifdef CONFIG_DEBUG_HIGHMEM
{
@@ -79,6 +79,8 @@ void __kunmap_atomic(void *kvaddr)
local_flush_tlb_page(NULL, vaddr);
}
#endif
+
+ kmap_atomic_idx_pop();
pagefault_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);
diff --git a/arch/sparc/mm/highmem.c b/arch/sparc/mm/highmem.c
index 5e50c09b7dc..4730eac0747 100644
--- a/arch/sparc/mm/highmem.c
+++ b/arch/sparc/mm/highmem.c
@@ -75,7 +75,7 @@ void __kunmap_atomic(void *kvaddr)
return;
}
- type = kmap_atomic_idx_pop();
+ type = kmap_atomic_idx();
#ifdef CONFIG_DEBUG_HIGHMEM
{
@@ -104,6 +104,8 @@ void __kunmap_atomic(void *kvaddr)
#endif
}
#endif
+
+ kmap_atomic_idx_pop();
pagefault_enable();
}
EXPORT_SYMBOL(__kunmap_atomic);
diff --git a/arch/tile/mm/highmem.c b/arch/tile/mm/highmem.c
index 8ef6595e162..abb57331cf6 100644
--- a/arch/tile/mm/highmem.c
+++ b/arch/tile/mm/highmem.c
@@ -241,7 +241,7 @@ void __kunmap_atomic(void *kvaddr)
pte_t pteval = *pte;
int idx, type;
- type = kmap_atomic_idx_pop();
+ type = kmap_atomic_idx();
idx = type + KM_TYPE_NR*smp_processor_id();
/*
@@ -252,6 +252,7 @@ void __kunmap_atomic(void *kvaddr)
BUG_ON(!pte_present(pteval) && !pte_migrating(pteval));
kmap_atomic_unregister(pte_page(pteval), vaddr);
kpte_clear_flush(pte, vaddr);
+ kmap_atomic_idx_pop();
} else {
/* Must be a lowmem page */
BUG_ON(vaddr < PAGE_OFFSET);
diff --git a/arch/x86/mm/highmem_32.c b/arch/x86/mm/highmem_32.c
index d723e369003..b4996266210 100644
--- a/arch/x86/mm/highmem_32.c
+++ b/arch/x86/mm/highmem_32.c
@@ -74,7 +74,7 @@ void __kunmap_atomic(void *kvaddr)
vaddr <= __fix_to_virt(FIX_KMAP_BEGIN)) {
int idx, type;
- type = kmap_atomic_idx_pop();
+ type = kmap_atomic_idx();
idx = type + KM_TYPE_NR * smp_processor_id();
#ifdef CONFIG_DEBUG_HIGHMEM
@@ -87,6 +87,7 @@ void __kunmap_atomic(void *kvaddr)
* attributes or becomes a protected page in a hypervisor.
*/
kpte_clear_flush(kmap_pte-idx, vaddr);
+ kmap_atomic_idx_pop();
}
#ifdef CONFIG_DEBUG_HIGHMEM
else {
diff --git a/arch/x86/mm/iomap_32.c b/arch/x86/mm/iomap_32.c
index 75a3d7f24a2..7b179b499fa 100644
--- a/arch/x86/mm/iomap_32.c
+++ b/arch/x86/mm/iomap_32.c
@@ -98,7 +98,7 @@ iounmap_atomic(void __iomem *kvaddr)
vaddr <= __fix_to_virt(FIX_KMAP_BEGIN)) {
int idx, type;
- type = kmap_atomic_idx_pop();
+ type = kmap_atomic_idx();
idx = type + KM_TYPE_NR * smp_processor_id();
#ifdef CONFIG_DEBUG_HIGHMEM
@@ -111,6 +111,7 @@ iounmap_atomic(void __iomem *kvaddr)
* attributes or becomes a protected page in a hypervisor.
*/
kpte_clear_flush(kmap_pte-idx, vaddr);
+ kmap_atomic_idx_pop();
}
pagefault_enable();