From a684d69d15a8fafede7c5c0daac8c646bbee805c Mon Sep 17 00:00:00 2001 From: Mark McLoughlin Date: Wed, 2 Apr 2008 15:36:37 +0100 Subject: [PATCH] xen: Do not pin/unpin PMD pages i.e. with this simple test case: int fd = open("/dev/zero", O_RDONLY); munmap(mmap((void *)0x40000000, 0x1000_LEN, PROT_READ, MAP_PRIVATE, fd, 0), 0x1000); close(fd); we currently get: kernel BUG at arch/x86/xen/enlighten.c:678! ... EIP is at xen_release_pt+0x79/0xa9 ... Call Trace: [] ? __pmd_free_tlb+0x1a/0x75 [] ? free_pgd_range+0x1d2/0x2b5 [] ? free_pgtables+0x7e/0x93 [] ? unmap_region+0xb9/0xf5 [] ? do_munmap+0x193/0x1f5 [] ? sys_munmap+0x30/0x3f [] ? syscall_call+0x7/0xb ======================= and xen complains: (XEN) mm.c:2241:d4 Mfn 1cc37 not pinned Further details at: https://bugzilla.redhat.com/436453 Signed-off-by: Mark McLoughlin Cc: xen-devel@lists.xensource.com Cc: Mark McLoughlin Cc: Jeremy Fitzhardinge Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar --- arch/x86/xen/enlighten.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index 16e2f8096a1a..f16b056e5c56 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -689,8 +689,6 @@ static void xen_alloc_ptpage(struct mm_struct *mm, u32 pfn, unsigned level) make_lowmem_page_readonly(__va(PFN_PHYS(pfn))); if (level == PT_PTE) pin_pagetable_pfn(MMUEXT_PIN_L1_TABLE, pfn); - else if (level == PT_PMD) - pin_pagetable_pfn(MMUEXT_PIN_L2_TABLE, pfn); } else /* make sure there are no stray mappings of this page */ @@ -715,7 +713,8 @@ static void xen_release_ptpage(u32 pfn, unsigned level) if (PagePinned(page)) { if (!PageHighMem(page)) { - pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, pfn); + if (level == PT_PTE) + pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, pfn); make_lowmem_page_readwrite(__va(PFN_PHYS(pfn))); } } -- 2.20.1