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| author | Christophe Leroy <christophe.leroy@csgroup.eu> | 2020-08-31 07:58:19 +0000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-09-15 22:13:30 +1000 |
| commit | 542db12a9c42d1ce70c45091765e02f74c129f43 (patch) | |
| tree | 9c3a88e027e53b86fee89670788c8b53a216aee1 /arch/powerpc/mm/hugetlbpage.c | |
| parent | e63d6fb5637e92725cf143559672a34b706bca4f (diff) | |
| download | linux-542db12a9c42d1ce70c45091765e02f74c129f43.tar.gz | |
powerpc: Fix random segfault when freeing hugetlb range
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@vger.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/f0cb2a5477cd87d1eaadb128042e20aeb2bc2859.1598860677.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch/powerpc/mm/hugetlbpage.c')
| -rw-r--r-- | arch/powerpc/mm/hugetlbpage.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c index 26292544630fb4..e7ae2a2c454503 100644 --- a/arch/powerpc/mm/hugetlbpage.c +++ b/arch/powerpc/mm/hugetlbpage.c @@ -330,10 +330,24 @@ static void free_hugepd_range(struct mmu_gather *tlb, hugepd_t *hpdp, int pdshif 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(struct mmu_gather *tlb, pud_t *pud, */ 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; } |