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Date:   Wed, 22 Nov 2023 17:08:17 +0200
From:   Mike Rapoport <rppt@kernel.org>
To:     Baoquan He <bhe@redhat.com>
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        akpm@linux-foundation.org
Subject: Re: [PATCH] mm/page.c: move mem_init_print_info() to later place
Message-ID: <20231122150817.GA634321@kernel.org>
References: <20231122043550.489889-1-bhe@redhat.com>
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Hi Baoquan,


On Wed, Nov 22, 2023 at 12:35:50PM +0800, Baoquan He wrote:

> Subject: [PATCH] mm/page.c: move mem_init_print_info() to later place

We don't have mm/page.c, 

> Currently if CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled, only part of
> pages are initialized and added into buddy allocator at early stage. Then
> the system memory information printed by mem_init_print_info() is
> incorrect. The snippets of boot log are pasted here:
> -----------------------------------------------------------------------
> [    0.059606] mem auto-init: stack:all(zero), heap alloc:off, heap free:off
> [    0.059622] software IO TLB: area num 64.
> [    0.143887] Memory: 1767888K/133954872K available (20480K kernel code, 3284K rwdata, 8972K rodata, 4572K init, 4916K bss, 2529756K reserved, 0K cma-reserved)
> [    0.145111] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=64, Nodes=2
> ---------------------------------------------------------------------------

At this point only the pages that were initialized and free are available.
The message does not reflect that large part of memory is still not initialized,
but it's not wrong.

> Here, move mem_init_print_info() to later place until page init is
> finished. After the fix, the printed memory information is like this:
> -------------------------------------------------------------------------
> [  +0.001002] smpboot: Total of 64 processors activated (293724.92 BogoMIPS)
> [  +0.050086] node 0 deferred pages initialised in 45ms
> [  +0.007309] node 1 deferred pages initialised in 53ms
> [    4.035449] Memory: 131272772K/133954872K available (20480K kernel code, 3284K rwdata, 8972K rodata, 4572K init, 4916K bss, 2529700K reserved, 0K cma-reserved)
> [  +0.015995] devtmpfs: initialized
> [  +0.003943] x86/mm: Memory block size: 2048MB
> -------------------------------------------------------------------------

If we print this message that late, some of the memory will be allocated
from buddy and it maybe confusing.

I suggest to print how much memory is not yet initialized and leave
mem_init_print_info() where it is now.
 
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  include/linux/gfp.h | 1 +
>  init/main.c         | 1 +
>  mm/mm_init.c        | 3 +--
>  3 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index de292a007138..2d69fa59b489 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -335,6 +335,7 @@ void drain_local_pages(struct zone *zone);
>  
>  void page_alloc_init_late(void);
>  void setup_pcp_cacheinfo(void);
> +void mem_init_print_info(void);
>  
>  /*
>   * gfp_allowed_mask is set to GFP_BOOT_MASK during early boot to restrict what
> diff --git a/init/main.c b/init/main.c
> index e24b0780fdff..88f238a478a1 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -1547,6 +1547,7 @@ static noinline void __init kernel_init_freeable(void)
>  	workqueue_init_topology();
>  	padata_init();
>  	page_alloc_init_late();
> +	mem_init_print_info();
  
No need to make mem_init_print_info() global and call it from main.c, you
can call it from page_alloc_init_late().

>  	do_basic_setup();
>  
> diff --git a/mm/mm_init.c b/mm/mm_init.c
> index 077bfe393b5e..d08f7c7f75f1 100644
> --- a/mm/mm_init.c
> +++ b/mm/mm_init.c
> @@ -2703,7 +2703,7 @@ static void __init report_meminit(void)
>  		pr_info("mem auto-init: clearing system memory may take some time...\n");
>  }
>  
> -static void __init mem_init_print_info(void)
> +void __init mem_init_print_info(void)
>  {
>  	unsigned long physpages, codesize, datasize, rosize, bss_size;
>  	unsigned long init_code_size, init_data_size;
> @@ -2774,7 +2774,6 @@ void __init mm_core_init(void)
>  	kmsan_init_shadow();
>  	stack_depot_early_init();
>  	mem_init();
> -	mem_init_print_info();
>  	kmem_cache_init();
>  	/*
>  	 * page_owner must be initialized after buddy is ready, and also after
> -- 
> 2.41.0
> 

-- 
Sincerely yours,
Mike.