From: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
commit 542db12a9c42d1ce70c45091765e02f74c129f43 upstream.
The following random segfault is observed from time to time with
map_hugetlb selftest:
root@localhost:~# ./map_hugetlb 1 19
524288 kB hugepages
Mapping 1 Mbytes
Segmentation fault
[ 31.219972] map_hugetlb[365]: segfault (11) at 117 nip 77974f8c lr 779a6834 code 1 in ld-2.23.so[77966000+21000]
[ 31.220192] map_hugetlb[365]: code: 9421ffc0 480318d1 93410028 90010044 9361002c 93810030 93a10034 93c10038
[ 31.220307] map_hugetlb[365]: code: 93e1003c 93210024 8123007c 81430038 <80e90004> 814a0004 7f443a14 813a0004
[ 31.221911] BUG: Bad rss-counter state mm:(ptrval) type:MM_FILEPAGES val:33
[ 31.229362] BUG: Bad rss-counter state mm:(ptrval) type:MM_ANONPAGES val:5
This fault is due to hugetlb_free_pgd_range() freeing page tables
that are also used by regular pages.
As explain in the comment at the beginning of
hugetlb_free_pgd_range(), the verification done in free_pgd_range()
on floor and ceiling is not done here, which means
hugetlb_free_pte_range() can free outside the expected range.
As the verification cannot be done in hugetlb_free_pgd_range(), it
must be done in hugetlb_free_pte_range().
Fixes: b250c8c08c79 ("powerpc/8xx: Manage 512k huge pages as standard pages.")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/f0cb2a5477cd87d1eaadb128042e20aeb2bc2859.1598860677.git.christophe.leroy@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/mm/hugetlbpage.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -330,10 +330,24 @@ static void free_hugepd_range(struct mmu
get_hugepd_cache_index(pdshift - shift));
}
-static void hugetlb_free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, unsigned long addr)
+static void hugetlb_free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
+ unsigned long addr, unsigned long end,
+ unsigned long floor, unsigned long ceiling)
{
+ unsigned long start = addr;
pgtable_t token = pmd_pgtable(*pmd);
+ start &= PMD_MASK;
+ if (start < floor)
+ return;
+ if (ceiling) {
+ ceiling &= PMD_MASK;
+ if (!ceiling)
+ return;
+ }
+ if (end - 1 > ceiling - 1)
+ return;
+
pmd_clear(pmd);
pte_free_tlb(tlb, token, addr);
mm_dec_nr_ptes(tlb->mm);
@@ -363,7 +377,7 @@ static void hugetlb_free_pmd_range(struc
*/
WARN_ON(!IS_ENABLED(CONFIG_PPC_8xx));
- hugetlb_free_pte_range(tlb, pmd, addr);
+ hugetlb_free_pte_range(tlb, pmd, addr, end, floor, ceiling);
continue;
}
