From 7c9dc749d0a5625ef1b76fbfa94c4845f998b44f Mon Sep 17 00:00:00 2001 From: Mika Westerberg Date: Thu, 28 Oct 2010 11:45:22 +0100 Subject: [PATCH] ARM: 6464/2: fix spinlock recursion in adjust_pte() commit 4e54d93d3c9846ba1c2644ad06463dafa690d1b7 upstream. 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 [] (unwind_backtrace+0x0/0xec) [] (do_raw_spin_lock+0x40/0x140) [] (update_mmu_cache+0x208/0x250) [] (__do_fault+0x320/0x3ec) [] (handle_mm_fault+0x2f0/0x6d8) [] (do_page_fault+0xdc/0x1cc) [] (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 Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman --- arch/arm/mm/fault-armv.c | 28 ++++++++++++++++++++++++++-- 1 file changed, 26 insertions(+), 2 deletions(-) diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c index 9b906dec1ca1..56036ff04deb 100644 --- a/arch/arm/mm/fault-armv.c +++ b/arch/arm/mm/fault-armv.c @@ -65,6 +65,30 @@ 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) { @@ -89,11 +113,11 @@ static int adjust_pte(struct vm_area_struct *vma, unsigned long address, */ ptl = pte_lockptr(vma->vm_mm, pmd); pte = pte_offset_map_nested(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_nested(pte); return ret; -- 2.34.1