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| author | Nicholas Piggin <npiggin@gmail.com> | 2017-11-10 04:27:37 +1100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-11-30 08:40:57 +0000 |
| commit | 34c8d3ffb64883b9279c03e79c1b08c9a1931940 (patch) | |
| tree | 8159d688ef91561d4f3bab89c8294368ed31c773 | |
| parent | 2279e9c895778cc8942b82e6e9fa153d5024acc2 (diff) | |
| download | linux-34c8d3ffb64883b9279c03e79c1b08c9a1931940.tar.gz linux-34c8d3ffb64883b9279c03e79c1b08c9a1931940.tar.bz2 linux-34c8d3ffb64883b9279c03e79c1b08c9a1931940.zip | |
powerpc/64s/hash: Fix fork() with 512TB process address space
commit effc1b25088502fbd30305c79773de2d1f7470a6 upstream.
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")
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -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 05e15386d4cb..b94fb62e60fd 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 |