Messages in this thread Patch in this message | | | Subject | [PATCH] mm: fix faulting range in do_fault_around | From | Konstantin Khlebnikov <> | Date | Tue, 15 Jul 2014 13:55:39 +0400 |
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From: Konstantin Khlebnikov <koct9i@gmail.com>
do_fault_around shoudn't cross pmd boundaries.
This patch does calculation in terms of addresses rather than pgoff. It looks much cleaner in this way. Probably it's worth to replace vmf->max_pgoff with vmf->end_address as well.
Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com> Reported-by: "Ingo Korb" <ingo.korb@tu-dortmund.de> --- mm/memory.c | 26 +++++++++++--------------- 1 file changed, 11 insertions(+), 15 deletions(-)
diff --git a/mm/memory.c b/mm/memory.c index d67fd9f..f27638a 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2831,33 +2831,29 @@ late_initcall(fault_around_debugfs); static void do_fault_around(struct vm_area_struct *vma, unsigned long address, pte_t *pte, pgoff_t pgoff, unsigned int flags) { - unsigned long start_addr; + unsigned long start_addr, end_addr; pgoff_t max_pgoff; struct vm_fault vmf; int off; - start_addr = max(address & fault_around_mask(), vma->vm_start); - off = ((address - start_addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); + start_addr = max3(vma->vm_start, address & PMD_MASK, + address & fault_around_mask()); + + end_addr = min3(vma->vm_end, ALIGN(address, PMD_SIZE), + start_addr + PAGE_ALIGN(fault_around_bytes)); + + off = (address - start_addr) >> PAGE_SHIFT; pte -= off; pgoff -= off; - - /* - * max_pgoff is either end of page table or end of vma - * or fault_around_pages() from pgoff, depending what is nearest. - */ - max_pgoff = pgoff - ((start_addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) + - PTRS_PER_PTE - 1; - max_pgoff = min3(max_pgoff, vma_pages(vma) + vma->vm_pgoff - 1, - pgoff + fault_around_pages() - 1); + max_pgoff = pgoff + ((end_addr - start_addr) >> PAGE_SHIFT) - 1; /* Check if it makes any sense to call ->map_pages */ while (!pte_none(*pte)) { - if (++pgoff > max_pgoff) - return; start_addr += PAGE_SIZE; - if (start_addr >= vma->vm_end) + if (start_addr >= end_addr) return; pte++; + pgoff++; } vmf.virtual_address = (void __user *) start_addr;
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