[PATCH] powerpc/mm: Fix kernel crash on page table free

[Christophe Leroy]

On 05/30/2018 12:32 PM, Aneesh Kumar K.V wrote:
> Fix the below crash on BookE 64. pgtable_page_dtor expects struct page *arg.
> 
> Also call the destructor on non book3s platforms correctly. This free up the
> split ptl locks correctly if we had allocated them before.
> 
> Call Trace:
> [c0000000f30c7520] [c00000000021eeec] .kmem_cache_free+0x9c/0x44c (unreliable)
> [c0000000f30c75c0] [c0000000001ee07c] .ptlock_free+0x1c/0x30
> [c0000000f30c7630] [c0000000001ee260] .tlb_remove_table+0xdc/0x224
> [c0000000f30c76c0] [c0000000001ee640] .free_pgd_range+0x298/0x500
> [c0000000f30c77d0] [c000000000232afc] .shift_arg_pages+0x10c/0x1e0
> [c0000000f30c7910] [c000000000232dd0] .setup_arg_pages+0x200/0x25c
> [c0000000f30c79c0] [c0000000002ad4fc] .load_elf_binary+0x450/0x16c8
> [c0000000f30c7b10] [c000000000234914] .search_binary_handler.part.11+0x9c/0x248
> [c0000000f30c7bb0] [c00000000023595c] .do_execveat_common.isra.13+0x868/0xc18
> [c0000000f30c7cb0] [c00000000000184c] .run_init_process+0x34/0x4c
> [c0000000f30c7d30] [c000000000001880] .try_to_run_init_process+0x1c/0x68
> [c0000000f30c7db0] [c000000000002bd8] .kernel_init+0xdc/0x130
> [c0000000f30c7e30] [c0000000000009dc] .ret_from_kernel_thread+0x58/0x7c
> 
> Fixes: 702346768 ("powerpc/mm/nohash: Remove pte fragment dependency from nohash")
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
> ---
>   arch/powerpc/include/asm/book3s/32/pgalloc.h | 1 +
>   arch/powerpc/include/asm/nohash/32/pgalloc.h | 1 +
>   arch/powerpc/include/asm/nohash/64/pgalloc.h | 2 +-
>   3 files changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/include/asm/book3s/32/pgalloc.h b/arch/powerpc/include/asm/book3s/32/pgalloc.h
> index 5073cc75f1c8..6a6673907e45 100644
> --- a/arch/powerpc/include/asm/book3s/32/pgalloc.h
> +++ b/arch/powerpc/include/asm/book3s/32/pgalloc.h
> @@ -99,6 +99,7 @@ static inline void pte_free(struct mm_struct *mm, pgtable_t ptepage)
>   static inline void pgtable_free(void *table, unsigned index_size)
>   {
>   	if (!index_size) {
> +		pgtable_page_dtor(virt_to_page(table));

__pte_free_tlb() already calls pgtable_page_dtor(table) before calling
pgtable_free() via pgtable_free_tlb().

Is it normal to call it twice ?

>   		free_page((unsigned long)table);
>   	} else {
>   		BUG_ON(index_size > MAX_PGTABLE_INDEX_SIZE);
> diff --git a/arch/powerpc/include/asm/nohash/32/pgalloc.h b/arch/powerpc/include/asm/nohash/32/pgalloc.h
> index 29d37bd1f3b3..1707781d2f20 100644
> --- a/arch/powerpc/include/asm/nohash/32/pgalloc.h
> +++ b/arch/powerpc/include/asm/nohash/32/pgalloc.h
> @@ -100,6 +100,7 @@ static inline void pte_free(struct mm_struct *mm, pgtable_t ptepage)
>   static inline void pgtable_free(void *table, unsigned index_size)
>   {
>   	if (!index_size) {
> +		pgtable_page_dtor(virt_to_page(table));

Same here

Christophe

>   		free_page((unsigned long)table);
>   	} else {
>   		BUG_ON(index_size > MAX_PGTABLE_INDEX_SIZE);
> diff --git a/arch/powerpc/include/asm/nohash/64/pgalloc.h b/arch/powerpc/include/asm/nohash/64/pgalloc.h
> index 21624ff1f065..0e693f322cb2 100644
> --- a/arch/powerpc/include/asm/nohash/64/pgalloc.h
> +++ b/arch/powerpc/include/asm/nohash/64/pgalloc.h
> @@ -133,7 +133,7 @@ static inline void pte_free(struct mm_struct *mm, pgtable_t ptepage)
>   static inline void pgtable_free(void *table, int shift)
>   {
>   	if (!shift) {
> -		pgtable_page_dtor(table);
> +		pgtable_page_dtor(virt_to_page(table));
>   		free_page((unsigned long)table);
>   	} else {
>   		BUG_ON(shift > MAX_PGTABLE_INDEX_SIZE);
>