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author | Mika Westerberg <mika.westerberg@iki.fi> | 2010-10-28 11:45:22 +0100 |
---|---|---|
committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2010-10-28 13:53:47 +0100 |
commit | 4e54d93d3c9846ba1c2644ad06463dafa690d1b7 (patch) | |
tree | 7d692f758a87fdc7d97caa3432542d08075eb427 | |
parent | 4e929d2bcf13eeaa9636448c55690b383a910391 (diff) | |
download | op-kernel-dev-4e54d93d3c9846ba1c2644ad06463dafa690d1b7.zip op-kernel-dev-4e54d93d3c9846ba1c2644ad06463dafa690d1b7.tar.gz |
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>
-rw-r--r-- | arch/arm/mm/fault-armv.c | 28 |
1 files changed, 26 insertions, 2 deletions
diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c index c493d72..83e59f8 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, return ret; } +#if USE_SPLIT_PTLOCKS +/* + * If we are using split PTE locks, then we need to take the page + * lock here. Otherwise we are using shared mm->page_table_lock + * which is already locked, thus cannot take it. + */ +static inline void do_pte_lock(spinlock_t *ptl) +{ + /* + * Use nested version here to indicate that we are already + * holding one similar spinlock. + */ + spin_lock_nested(ptl, SINGLE_DEPTH_NESTING); +} + +static inline void do_pte_unlock(spinlock_t *ptl) +{ + spin_unlock(ptl); +} +#else /* !USE_SPLIT_PTLOCKS */ +static inline void do_pte_lock(spinlock_t *ptl) {} +static inline void do_pte_unlock(spinlock_t *ptl) {} +#endif /* USE_SPLIT_PTLOCKS */ + static int adjust_pte(struct vm_area_struct *vma, unsigned long address, unsigned long pfn) { @@ -90,11 +114,11 @@ static int adjust_pte(struct vm_area_struct *vma, unsigned long address, */ ptl = pte_lockptr(vma->vm_mm, pmd); pte = pte_offset_map(pmd, address); - spin_lock(ptl); + do_pte_lock(ptl); ret = do_adjust_pte(vma, address, pfn, pte); - spin_unlock(ptl); + do_pte_unlock(ptl); pte_unmap(pte); return ret; |