linux-kernel - Re: [PATCH 2/5] mm/madvise: thread mm_struct through madvise

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Message-ID: <B4B8173E-F592-4CEE-B35E-BFC6B2CDDFB8@nvidia.com>
Date: Thu, 19 Jun 2025 21:40:34 -0400
From: Zi Yan <ziy@...dia.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
 David Hildenbrand <david@...hat.com>,
 Baolin Wang <baolin.wang@...ux.alibaba.com>,
 "Liam R . Howlett" <Liam.Howlett@...cle.com>, Nico Pache <npache@...hat.com>,
 Ryan Roberts <ryan.roberts@....com>, Dev Jain <dev.jain@....com>,
 Barry Song <baohua@...nel.org>, Vlastimil Babka <vbabka@...e.cz>,
 Jann Horn <jannh@...gle.com>, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, Lance Yang <ioworker0@...il.com>,
 SeongJae Park <sj@...nel.org>, Suren Baghdasaryan <surenb@...gle.com>
Subject: Re: [PATCH 2/5] mm/madvise: thread mm_struct through madvise_behavior

On 19 Jun 2025, at 16:26, Lorenzo Stoakes wrote:

> There's no need to thread a pointer to the mm_struct nor have different
> functions signatures for each behaviour, instead store state in the struct
> madvise_behavior object consistently and use it for all madvise() actions.
>
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> ---
>  mm/madvise.c | 105 ++++++++++++++++++++++++++-------------------------
>  1 file changed, 54 insertions(+), 51 deletions(-)
>

<snip>

> @@ -1422,15 +1425,14 @@ static int madvise_vma_behavior(struct vm_area_struct *vma,
>  /*
>   * Error injection support for memory error handling.
>   */
> -static int madvise_inject_error(int behavior,
> -		unsigned long start, unsigned long end)
> +static int madvise_inject_error(unsigned long start, unsigned long end,
> +		struct madvise_behavior *madv_behavior)
>  {
>  	unsigned long size;
>
>  	if (!capable(CAP_SYS_ADMIN))
>  		return -EPERM;
>
> -
>  	for (; start < end; start += size) {
>  		unsigned long pfn;
>  		struct page *page;
> @@ -1448,7 +1450,7 @@ static int madvise_inject_error(int behavior,
>  		 */
>  		size = page_size(compound_head(page));
>
> -		if (behavior == MADV_SOFT_OFFLINE) {
> +		if (madv_behavior->behavior == MADV_SOFT_OFFLINE) {
>  			pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
>  				 pfn, start);
>  			ret = soft_offline_page(pfn, MF_COUNT_INCREASED);
> @@ -1467,9 +1469,9 @@ static int madvise_inject_error(int behavior,
>  	return 0;
>  }
>

Is this necessary? madvise_inject_error() only cares about behavior.

> -static bool is_memory_failure(int behavior)
> +static bool is_memory_failure(struct madvise_behavior *madv_behavior)
>  {
> -	switch (behavior) {
> +	switch (madv_behavior->behavior) {
>  	case MADV_HWPOISON:
>  	case MADV_SOFT_OFFLINE:
>  		return true;
> @@ -1480,13 +1482,13 @@ static bool is_memory_failure(int behavior)
>
>  #else
>
> -static int madvise_inject_error(int behavior,
> -		unsigned long start, unsigned long end)
> +static int madvise_inject_error(unsigned long start, unsigned long end,
> +		struct madvise_behavior *madv_behavior)
>  {
>  	return 0;
>  }
>
> -static bool is_memory_failure(int behavior)
> +static bool is_memory_failure(struct madvise_behavior *madv_behavior)
>  {
>  	return false;
>  }

Same here. Your is_anon_vma_name() still takes int behavior, why
would is_memory_failure() take struct madvise_behavior?

<snip>

> -static bool is_madvise_populate(int behavior)
> +static bool is_madvise_populate(struct madvise_behavior *madv_behavior)
>  {
> -	switch (behavior) {
> +	switch (madv_behavior->behavior) {
>  	case MADV_POPULATE_READ:
>  	case MADV_POPULATE_WRITE:
>  		return true;

Ditto.

The rest looks good to me.

--
Best Regards,
Yan, Zi