diff options
| author | Dan Williams <dan.j.williams@intel.com> | 2020-12-03 09:28:12 +0300 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2021-01-05 13:40:23 +0300 |
| commit | d1c5246e08eb64991001d97a3bd119c93edbc79a (patch) | |
| tree | 323f620ff7e2f92b7699b9c334176392c053a4f5 /arch | |
| parent | 2ca408d9c749c32288bc28725f9f12ba30299e8f (diff) | |
| download | linux-d1c5246e08eb64991001d97a3bd119c93edbc79a.tar.xz | |
x86/mm: Fix leak of pmd ptlock
Commit
28ee90fe6048 ("x86/mm: implement free pmd/pte page interfaces")
introduced a new location where a pmd was released, but neglected to
run the pmd page destructor. In fact, this happened previously for a
different pmd release path and was fixed by commit:
c283610e44ec ("x86, mm: do not leak page->ptl for pmd page tables").
This issue was hidden until recently because the failure mode is silent,
but commit:
b2b29d6d0119 ("mm: account PMD tables like PTE tables")
turns the failure mode into this signature:
BUG: Bad page state in process lt-pmem-ns pfn:15943d
page:000000007262ed7b refcount:0 mapcount:-1024 mapping:0000000000000000 index:0x0 pfn:0x15943d
flags: 0xaffff800000000()
raw: 00affff800000000 dead000000000100 0000000000000000 0000000000000000
raw: 0000000000000000 ffff913a029bcc08 00000000fffffbff 0000000000000000
page dumped because: nonzero mapcount
[..]
dump_stack+0x8b/0xb0
bad_page.cold+0x63/0x94
free_pcp_prepare+0x224/0x270
free_unref_page+0x18/0xd0
pud_free_pmd_page+0x146/0x160
ioremap_pud_range+0xe3/0x350
ioremap_page_range+0x108/0x160
__ioremap_caller.constprop.0+0x174/0x2b0
? memremap+0x7a/0x110
memremap+0x7a/0x110
devm_memremap+0x53/0xa0
pmem_attach_disk+0x4ed/0x530 [nd_pmem]
? __devm_release_region+0x52/0x80
nvdimm_bus_probe+0x85/0x210 [libnvdimm]
Given this is a repeat occurrence it seemed prudent to look for other
places where this destructor might be missing and whether a better
helper is needed. try_to_free_pmd_page() looks like a candidate, but
testing with setting up and tearing down pmd mappings via the dax unit
tests is thus far not triggering the failure.
As for a better helper pmd_free() is close, but it is a messy fit
due to requiring an @mm arg. Also, ___pmd_free_tlb() wants to call
paravirt_tlb_remove_table() instead of free_page(), so open-coded
pgtable_pmd_page_dtor() seems the best way forward for now.
Debugged together with Matthew Wilcox <willy@infradead.org>.
Fixes: 28ee90fe6048 ("x86/mm: implement free pmd/pte page interfaces")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/160697689204.605323.17629854984697045602.stgit@dwillia2-desk3.amr.corp.intel.com
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/mm/pgtable.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index dfd82f51ba66..f6a9e2e36642 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -829,6 +829,8 @@ int pud_free_pmd_page(pud_t *pud, unsigned long addr) } free_page((unsigned long)pmd_sv); + + pgtable_pmd_page_dtor(virt_to_page(pmd)); free_page((unsigned long)pmd); return 1; |