Messages in this thread | | | Subject | Re: [PATCH] mm/pgtable/debug: Fix test validating architecture page table helpers | From | Christophe Leroy <> | Date | Fri, 13 Sep 2019 09:11:49 +0200 |
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Le 13/09/2019 à 09:03, Christophe Leroy a écrit : > > > Le 13/09/2019 à 08:58, Anshuman Khandual a écrit : >> On 09/13/2019 11:53 AM, Christophe Leroy wrote: >>> Fix build failure on powerpc. >>> >>> Fix preemption imbalance. >>> >>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> >>> --- >>> mm/arch_pgtable_test.c | 3 +++ >>> 1 file changed, 3 insertions(+) >>> >>> diff --git a/mm/arch_pgtable_test.c b/mm/arch_pgtable_test.c >>> index 8b4a92756ad8..f2b3c9ec35fa 100644 >>> --- a/mm/arch_pgtable_test.c >>> +++ b/mm/arch_pgtable_test.c >>> @@ -24,6 +24,7 @@ >>> #include <linux/swap.h> >>> #include <linux/swapops.h> >>> #include <linux/sched/mm.h> >>> +#include <linux/highmem.h> >> >> This is okay. >> >>> #include <asm/pgalloc.h> >>> #include <asm/pgtable.h> >>> @@ -400,6 +401,8 @@ static int __init arch_pgtable_tests_init(void) >>> p4d_clear_tests(p4dp); >>> pgd_clear_tests(mm, pgdp); >>> + pte_unmap(ptep); >>> + >> >> Now the preemption imbalance via pte_alloc_map() path i.e >> >> pte_alloc_map() -> pte_offset_map() -> kmap_atomic() >> >> Is not this very much powerpc 32 specific or this will be applicable >> for all platform which uses kmap_XXX() to map high memory ? >> > > See > https://elixir.bootlin.com/linux/v5.3-rc8/source/include/linux/highmem.h#L91 > > > I think it applies at least to all arches using the generic implementation. > > Applies also to arm: > https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/arm/mm/highmem.c#L52 > > Applies also to mips: > https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/mips/mm/highmem.c#L47 > > Same on sparc: > https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/sparc/mm/highmem.c#L52 > > > Same on x86: > https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/x86/mm/highmem_32.c#L34 > > > I have not checked others, but I guess it is like that for all. >
Seems like I answered too quickly. All kmap_atomic() do preempt_disable(), but not all pte_alloc_map() call kmap_atomic().
However, for instance ARM does:
https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/arm/include/asm/pgtable.h#L200
And X86 as well:
https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/x86/include/asm/pgtable_32.h#L51
Microblaze also:
https://elixir.bootlin.com/linux/v5.3-rc8/source/arch/microblaze/include/asm/pgtable.h#L495
Christophe
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