diff options
| author | Nicholas Piggin <npiggin@gmail.com> | 2017-11-10 04:27:37 +1100 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-11-13 23:34:47 +1100 |
| commit | effc1b25088502fbd30305c79773de2d1f7470a6 (patch) | |
| tree | 445876663d30bc964374a77c90422b2d456e0860 | |
| parent | 6a72dc038b615229a1b285829d6c8378d15c2347 (diff) | |
| download | linux-effc1b25088502fbd30305c79773de2d1f7470a6.tar.bz2 | |
powerpc/64s/hash: Fix fork() with 512TB process address space
Hash unconditionally resets the addr_limit to default (128TB) when the
mm context is initialised. If a process has > 128TB mappings when it
forks, the child will not get the 512TB addr_limit, so accesses to
valid > 128TB mappings will fail in the child.
Fix this by only resetting the addr_limit to default if it was 0. Non
zero indicates it was duplicated from the parent (0 means exec()).
Fixes: f4ea6dcb08ea ("powerpc/mm: Enable mappings above 128TB")
Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
| -rw-r--r-- | arch/powerpc/mm/mmu_context_book3s64.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/powerpc/mm/mmu_context_book3s64.c b/arch/powerpc/mm/mmu_context_book3s64.c index 6d724dab27c2..846cbad45fce 100644 --- a/arch/powerpc/mm/mmu_context_book3s64.c +++ b/arch/powerpc/mm/mmu_context_book3s64.c @@ -93,11 +93,11 @@ static int hash__init_new_context(struct mm_struct *mm) return index; /* - * We do switch_slb() early in fork, even before we setup the - * mm->context.addr_limit. Default to max task size so that we copy the - * default values to paca which will help us to handle slb miss early. + * In the case of exec, use the default limit, + * otherwise inherit it from the mm we are duplicating. */ - mm->context.addr_limit = DEFAULT_MAP_WINDOW_USER64; + if (!mm->context.addr_limit) + mm->context.addr_limit = DEFAULT_MAP_WINDOW_USER64; /* * The old code would re-promote on fork, we don't do that when using |