| Message ID | 20171106100315.29720-4-npiggin@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | VA allocator fixes | expand |
Nicholas Piggin <npiggin@gmail.com> writes: > 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()). > Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> > Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> > Fixes: f4ea6dcb08 ("powerpc/mm: Enable mappings above 128TB") > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> > --- > arch/powerpc/mm/mmu_context_book3s64.c | 8 ++++---- > 1 file 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 > -- > 2.15.0
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
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()). Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> Fixes: f4ea6dcb08 ("powerpc/mm: Enable mappings above 128TB") Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/mm/mmu_context_book3s64.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)