On Fri, Oct 16, 2020 at 05:14:00PM +0800, Zhenhua Huang wrote:
> Page owner of pages used by page owner itself used is missing on arm32 targets.
> The reason is dummy_handle and failure_handle is not initialized correctly.
> Buddy allocator is used to initialize these two handles. However, buddy
> allocator is not ready when page owner calls it. This change fixed that by
> initializing page owner after buddy initialization.
>
> The working flow before and after this change are:
> original logic:
> 1. allocated memory for page_ext(using memblock).
Is anything that requires a memblock allocation FLATMEM?
Any fundamental reason why wouldn't alloc_pages_exact_nid/vzalloc_node()
work in this case?
It seems to me that for FLATMEM configuration we can allocate the
page_ext using alloc_pages() with a fallback to vzalloc_node() and then
we can unify lot's of page_ext code and entirely drop
page_ext_init_flatmem().
> 2. invoke the init callback of page_ext_ops like
> page_owner(using buddy allocator).
> 3. initialize buddy.
>
> after this change:
> 1. allocated memory for page_ext(using memblock).
> 2. initialize buddy.
> 3. invoke the init callback of page_ext_ops like
> page_owner(using buddy allocator).
>
> with the change, failure/dummy_handle can get its correct value and
> page owner output for example has the one for page owner itself:
> Page allocated via order 2, mask 0x6202c0(GFP_USER|__GFP_NOWARN), pid 1006, ts
> 67278156558 ns
> PFN 543776 type Unmovable Block 531 type Unmovable Flags 0x0()
> init_page_owner+0x28/0x2f8
> invoke_init_callbacks_flatmem+0x24/0x34
> start_kernel+0x33c/0x5d8
> (null)
>
> Signed-off-by: Zhenhua Huang <zhenhuah@xxxxxxxxxxxxxx>
> ---
> include/linux/page_ext.h | 8 ++++++++
> init/main.c | 2 ++
> mm/page_ext.c | 8 +++++++-
> 3 files changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h
> index cfce186..aff81ba 100644
> --- a/include/linux/page_ext.h
> +++ b/include/linux/page_ext.h
> @@ -44,8 +44,12 @@ static inline void page_ext_init_flatmem(void)
> {
> }
> extern void page_ext_init(void);
> +static inline void page_ext_init_flatmem_late(void)
> +{
> +}
> #else
> extern void page_ext_init_flatmem(void);
> +extern void page_ext_init_flatmem_late(void);
> static inline void page_ext_init(void)
> {
> }
> @@ -76,6 +80,10 @@ static inline void page_ext_init(void)
> {
> }
>
> +static inline void page_ext_init_flatmem_late(void)
> +{
> +}
> +
> static inline void page_ext_init_flatmem(void)
> {
> }
> diff --git a/init/main.c b/init/main.c
> index 130376e..b34c475 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -818,6 +818,8 @@ static void __init mm_init(void)
> init_debug_pagealloc();
> report_meminit();
> mem_init();
> + /* page_owner must be initialized after buddy is ready */
> + page_ext_init_flatmem_late();
> kmem_cache_init();
> kmemleak_init();
> pgtable_init();
> diff --git a/mm/page_ext.c b/mm/page_ext.c
> index a3616f7..373f7a1 100644
> --- a/mm/page_ext.c
> +++ b/mm/page_ext.c
> @@ -99,6 +99,13 @@ static void __init invoke_init_callbacks(void)
> }
> }
>
> +#if !defined(CONFIG_SPARSEMEM)
> +void __init page_ext_init_flatmem_late(void)
> +{
> + invoke_init_callbacks();
> +}
> +#endif
> +
> static inline struct page_ext *get_entry(void *base, unsigned long index)
> {
> return base + page_ext_size * index;
> @@ -177,7 +184,6 @@ void __init page_ext_init_flatmem(void)
> goto fail;
> }
> pr_info("allocated %ld bytes of page_ext\n", total_usage);
> - invoke_init_callbacks();
> return;
>
> fail:
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>
>
--
Sincerely yours,
Mike.
