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author | Josh Boyer <jwboyer@redhat.com> | 2013-02-26 08:14:54 -0500 |
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committer | Josh Boyer <jwboyer@redhat.com> | 2013-02-26 08:17:31 -0500 |
commit | 318f6554a39314d9f24636b448e38ccaea461d21 (patch) | |
tree | 773e6c29e8468d23bba12c9ff8cf727e596328c9 /x86-mm-Fix-vmalloc_fault-oops-during-lazy-MMU-updates.patch | |
parent | c040d8cac33ad4e991767be5acc66a8fada2a0a1 (diff) | |
download | kernel-318f6554a39314d9f24636b448e38ccaea461d21.tar.gz kernel-318f6554a39314d9f24636b448e38ccaea461d21.tar.xz kernel-318f6554a39314d9f24636b448e38ccaea461d21.zip |
Fix vmalloc_fault oops during lazy MMU (rhbz 914737)
Diffstat (limited to 'x86-mm-Fix-vmalloc_fault-oops-during-lazy-MMU-updates.patch')
-rw-r--r-- | x86-mm-Fix-vmalloc_fault-oops-during-lazy-MMU-updates.patch | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/x86-mm-Fix-vmalloc_fault-oops-during-lazy-MMU-updates.patch b/x86-mm-Fix-vmalloc_fault-oops-during-lazy-MMU-updates.patch new file mode 100644 index 000000000..31b0de8fb --- /dev/null +++ b/x86-mm-Fix-vmalloc_fault-oops-during-lazy-MMU-updates.patch @@ -0,0 +1,48 @@ +From: Samu Kallio <> +Subject: [PATCH] x86: mm: Fix vmalloc_fault oops during lazy MMU updates. +Date: Sun, 17 Feb 2013 04:35:52 +0200 + +In paravirtualized x86_64 kernels, vmalloc_fault may cause an oops +when lazy MMU updates are enabled, because set_pgd effects are being +deferred. + +One instance of this problem is during process mm cleanup with memory +cgroups enabled. The chain of events is as follows: + +- zap_pte_range enables lazy MMU updates +- zap_pte_range eventually calls mem_cgroup_charge_statistics, + which accesses the vmalloc'd mem_cgroup per-cpu stat area +- vmalloc_fault is triggered which tries to sync the corresponding + PGD entry with set_pgd, but the update is deferred +- vmalloc_fault oopses due to a mismatch in the PUD entries + +Calling arch_flush_lazy_mmu_mode immediately after set_pgd makes the +changes visible to the consistency checks. + +Signed-off-by: Samu Kallio <samu.kallio@aberdeencloud.com> +--- + arch/x86/mm/fault.c | 6 ++++-- + 1 file changed, 4 insertions(+), 2 deletions(-) +diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c +index 8e13ecb..0a45298 100644 +--- a/arch/x86/mm/fault.c ++++ b/arch/x86/mm/fault.c +@@ -378,10 +378,12 @@ static noinline __kprobes int vmalloc_fault(unsigned long address) + if (pgd_none(*pgd_ref)) + return -1; + +- if (pgd_none(*pgd)) ++ if (pgd_none(*pgd)) { + set_pgd(pgd, *pgd_ref); +- else ++ arch_flush_lazy_mmu_mode(); ++ } else { + BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref)); ++ } + + /* + * Below here mismatches are bugs because these lower tables +-- +1.8.1.3 + + |