[PATCH v2 01/23] arm: allow pte_offset_map[_lock]() to fail
Hugh Dickins <[email protected]>
| Newsgroups | gmane.linux.ports.ia64,gmane.linux.ports.arm.kernel,gmane.linux.ports.mips,gmane.linux.ports.parisc,gmane.linux.ports.ppc64.devel,gmane.linux.ports.riscv,gmane.linux.ports.sh.devel,gmane.linux.ports.sparc,gmane.linux.kernel,gmane.linux.kernel.mm |
|---|---|
| Message-ID | <[email protected]> |
In rare transient cases, not yet made possible, pte_offset_map() and pte_offset_map_lock() may not find a page table: handle appropriately. Signed-off-by: Hugh Dickins <[email protected]> --- arch/arm/lib/uaccess_with_memcpy.c | 3 +++ arch/arm/mm/fault-armv.c | 5 ++++- arch/arm/mm/fault.c | 3 +++ 3 files changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/arm/lib/uaccess_with_memcpy.c b/arch/arm/lib/uaccess_with_memcpy.c index e4c2677cc1e9..2f6163f05e93 100644 --- a/arch/arm/lib/uaccess_with_memcpy.c +++ b/arch/arm/lib/uaccess_with_memcpy.c @@ -74,6 +74,9 @@ pin_page_for_write(const void __user *_addr, pte_t **ptep, spinlock_t **ptlp) return 0; pte = pte_offset_map_lock(current->mm, pmd, addr, &ptl); + if (unlikely(!pte)) + return 0; + if (unlikely(!pte_present(*pte) || !pte_young(*pte) || !pte_write(*pte) || !pte_dirty(*pte))) { pte_unmap_unlock(pte, ptl); diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c index 0e49154454a6..ca5302b0b7ee 100644 --- a/arch/arm/mm/fault-armv.c +++ b/arch/arm/mm/fault-armv.c @@ -117,8 +117,11 @@ static int adjust_pte(struct vm_area_struct *vma, unsigned long address, * must use the nested version. This also means we need to * open-code the spin-locking. */ - ptl = pte_lockptr(vma->vm_mm, pmd); pte = pte_offset_map(pmd, address); + if (!pte) + return 0; + + ptl = pte_lockptr(vma->vm_mm, pmd); do_pte_lock(ptl); ret = do_adjust_pte(vma, address, pfn, pte); diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c index 2418f1efabd8..83598649a094 100644 --- a/arch/arm/mm/fault.c +++ b/arch/arm/mm/fault.c @@ -85,6 +85,9 @@ void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr) break; pte = pte_offset_map(pmd, addr); + if (!pte) + break; + pr_cont(", *pte=%08llx", (long long)pte_val(*pte)); #ifndef CONFIG_ARM_LPAE pr_cont(", *ppte=%08llx", -- 2.35.3