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author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2010-10-27 15:32:58 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-10-27 18:03:05 -0700 |
commit | 20273941f2129aa5a432796d98a276ed73d60782 (patch) | |
tree | 85da0d951ac10f239f81ad7f69559fdeb692095b /arch | |
parent | a8e23a291852cd7c4fb5ca696dbb93912185ad10 (diff) | |
download | lwn-20273941f2129aa5a432796d98a276ed73d60782.tar.gz lwn-20273941f2129aa5a432796d98a276ed73d60782.zip |
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.c | 3 | ||||
-rw-r--r-- | arch/frv/mm/highmem.c | 3 | ||||
-rw-r--r-- | arch/mips/mm/highmem.c | 3 | ||||
-rw-r--r-- | arch/mn10300/include/asm/highmem.h | 4 | ||||
-rw-r--r-- | arch/powerpc/mm/highmem.c | 4 | ||||
-rw-r--r-- | arch/sparc/mm/highmem.c | 4 | ||||
-rw-r--r-- | arch/tile/mm/highmem.c | 3 | ||||
-rw-r--r-- | arch/x86/mm/highmem_32.c | 3 | ||||
-rw-r--r-- | arch/x86/mm/iomap_32.c | 3 |
9 files changed, 21 insertions, 9 deletions
diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c index c00f119babbf..c435fd9e1da9 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 61088dcc1594..fd7fcd4c2e33 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 1e69b1fb4b85..3634c7ea06ac 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 f577ba2268ca..e2155e686451 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 b0848b462bbc..e7450bdbe83a 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 5e50c09b7dce..4730eac0747b 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 8ef6595e162c..abb57331cf6e 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 d723e369003c..b49962662101 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 75a3d7f24a2c..7b179b499fa3 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(); |