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authorMika Westerberg <mika.westerberg@iki.fi>2010-10-28 06:45:22 -0400
committerRussell King <rmk+kernel@arm.linux.org.uk>2010-10-28 08:53:47 -0400
commit4e54d93d3c9846ba1c2644ad06463dafa690d1b7 (patch)
tree7d692f758a87fdc7d97caa3432542d08075eb427 /arch/arm/mm/fault-armv.c
parent4e929d2bcf13eeaa9636448c55690b383a910391 (diff)
ARM: 6464/2: fix spinlock recursion in adjust_pte()
When running following code in a machine which has VIVT caches and USE_SPLIT_PTLOCKS is not defined: fd = open("/etc/passwd", O_RDONLY); addr = mmap(NULL, 4096, PROT_READ, MAP_SHARED, fd, 0); addr2 = mmap(NULL, 4096, PROT_READ, MAP_SHARED, fd, 0); v = *((int *)addr); we will hang in spinlock recursion in the page fault handler: BUG: spinlock recursion on CPU#0, mmap_test/717 lock: c5e295d8, .magic: dead4ead, .owner: mmap_test/717, .owner_cpu: 0 [<c0026604>] (unwind_backtrace+0x0/0xec) [<c014ee48>] (do_raw_spin_lock+0x40/0x140) [<c0027f68>] (update_mmu_cache+0x208/0x250) [<c0079db4>] (__do_fault+0x320/0x3ec) [<c007af7c>] (handle_mm_fault+0x2f0/0x6d8) [<c0027834>] (do_page_fault+0xdc/0x1cc) [<c00202d0>] (do_DataAbort+0x34/0x94) This comes from the fact that when USE_SPLIT_PTLOCKS is not defined, the only lock protecting the page tables is mm->page_table_lock which is already locked before update_mmu_cache() is called. Signed-off-by: Mika Westerberg <mika.westerberg@iki.fi> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/mm/fault-armv.c')
-rw-r--r--arch/arm/mm/fault-armv.c28
1 files changed, 26 insertions, 2 deletions
diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c
index c493d7244d3d..83e59f870426 100644
--- a/arch/arm/mm/fault-armv.c
+++ b/arch/arm/mm/fault-armv.c
@@ -66,6 +66,30 @@ static int do_adjust_pte(struct vm_area_struct *vma, unsigned long address,
66 return ret; 66 return ret;
67} 67}
68 68
69#if USE_SPLIT_PTLOCKS
70/*
71 * If we are using split PTE locks, then we need to take the page
72 * lock here. Otherwise we are using shared mm->page_table_lock
73 * which is already locked, thus cannot take it.
74 */
75static inline void do_pte_lock(spinlock_t *ptl)
76{
77 /*
78 * Use nested version here to indicate that we are already
79 * holding one similar spinlock.
80 */
81 spin_lock_nested(ptl, SINGLE_DEPTH_NESTING);
82}
83
84static inline void do_pte_unlock(spinlock_t *ptl)
85{
86 spin_unlock(ptl);
87}
88#else /* !USE_SPLIT_PTLOCKS */
89static inline void do_pte_lock(spinlock_t *ptl) {}
90static inline void do_pte_unlock(spinlock_t *ptl) {}
91#endif /* USE_SPLIT_PTLOCKS */
92
69static int adjust_pte(struct vm_area_struct *vma, unsigned long address, 93static int adjust_pte(struct vm_area_struct *vma, unsigned long address,
70 unsigned long pfn) 94 unsigned long pfn)
71{ 95{
@@ -90,11 +114,11 @@ static int adjust_pte(struct vm_area_struct *vma, unsigned long address,
90 */ 114 */
91 ptl = pte_lockptr(vma->vm_mm, pmd); 115 ptl = pte_lockptr(vma->vm_mm, pmd);
92 pte = pte_offset_map(pmd, address); 116 pte = pte_offset_map(pmd, address);
93 spin_lock(ptl); 117 do_pte_lock(ptl);
94 118
95 ret = do_adjust_pte(vma, address, pfn, pte); 119 ret = do_adjust_pte(vma, address, pfn, pte);
96 120
97 spin_unlock(ptl); 121 do_pte_unlock(ptl);
98 pte_unmap(pte); 122 pte_unmap(pte);
99 123
100 return ret; 124 return ret;