[PATCH mm-unstable] mm: thp: fix build error with CONFIG_SHMEM disabled

[Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>]

From 9075ff5ab459b1b1df53e74261d24f300203ee9f Mon Sep 17 00:00:00 2001
From: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Date: Thu, 1 Sep 2022 07:26:25 +0000
Subject: [PATCH mm-unstable] mm: thp: fix build error with CONFIG_SHMEM
 disabled

Fix the following build error by changing function
parameter type from struct mm_sot * to struct khugepaged_mm_slot *:

mm/khugepaged.c: In function 'khugepaged_scan_mm_slot':
>> mm/khugepaged.c:2056:45: error: passing argument 1 of 
'khugepaged_collapse_pte_mapped_thps' from incompatible pointer type 
[-Werror=incompatible-pointer-types]
    2056 |         khugepaged_collapse_pte_mapped_thps(mm_slot);
         |                                             ^~~~~~~
         |                                             |
         |                                             struct 
khugepaged_mm_slot *
   mm/khugepaged.c:2023:65: note: expected 'struct mm_slot *' but 
argument is of type 'struct khugepaged_mm_slot *'
    2023 | static void khugepaged_collapse_pte_mapped_thps(struct 
mm_slot *mm_slot)
         | 
~~~~~~~~~~~~~~~~^~~~~~~
   cc1: some warnings being treated as errors

Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
---
 mm/khugepaged.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 2d74cf01f694..af3b07eb2389 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -2020,7 +2020,7 @@ static int khugepaged_scan_file(struct mm_struct 
*mm, struct file *file,
 	BUILD_BUG();
 }

-static void khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot)
+static void khugepaged_collapse_pte_mapped_thps(struct 
khugepaged_mm_slot *mm_slot)
 {
 }
 #endif
--
2.20.1


On 2022/8/31 11:19, Qi Zheng wrote:
> Rename private struct mm_slot to struct khugepaged_mm_slot and
> convert to use common struct mm_slot with no functional change.
>
> Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
> ---
>   mm/khugepaged.c | 121 ++++++++++++++++++++----------------------------
>   1 file changed, 51 insertions(+), 70 deletions(-)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index d8e388106322..2d74cf01f694 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -23,6 +23,7 @@
>   #include <asm/tlb.h>
>   #include <asm/pgalloc.h>
>   #include "internal.h"
> +#include "mm_slot.h"
>   
>   enum scan_result {
>   	SCAN_FAIL,
> @@ -104,17 +105,13 @@ struct collapse_control {
>   };
>   
>   /**
> - * struct mm_slot - hash lookup from mm to mm_slot
> - * @hash: hash collision list
> - * @mm_node: khugepaged scan list headed in khugepaged_scan.mm_head
> - * @mm: the mm that this information is valid for
> + * struct khugepaged_mm_slot - khugepaged information per mm that is being scanned
> + * @slot: hash lookup from mm to mm_slot
>    * @nr_pte_mapped_thp: number of pte mapped THP
>    * @pte_mapped_thp: address array corresponding pte mapped THP
>    */
> -struct mm_slot {
> -	struct hlist_node hash;
> -	struct list_head mm_node;
> -	struct mm_struct *mm;
> +struct khugepaged_mm_slot {
> +	struct mm_slot slot;
>   
>   	/* pte-mapped THP in this mm */
>   	int nr_pte_mapped_thp;
> @@ -131,7 +128,7 @@ struct mm_slot {
>    */
>   struct khugepaged_scan {
>   	struct list_head mm_head;
> -	struct mm_slot *mm_slot;
> +	struct khugepaged_mm_slot *mm_slot;
>   	unsigned long address;
>   };
>   
> @@ -395,8 +392,9 @@ int hugepage_madvise(struct vm_area_struct *vma,
>   int __init khugepaged_init(void)
>   {
>   	mm_slot_cache = kmem_cache_create("khugepaged_mm_slot",
> -					  sizeof(struct mm_slot),
> -					  __alignof__(struct mm_slot), 0, NULL);
> +					  sizeof(struct khugepaged_mm_slot),
> +					  __alignof__(struct khugepaged_mm_slot),
> +					  0, NULL);
>   	if (!mm_slot_cache)
>   		return -ENOMEM;
>   
> @@ -413,36 +411,6 @@ void __init khugepaged_destroy(void)
>   	kmem_cache_destroy(mm_slot_cache);
>   }
>   
> -static inline struct mm_slot *alloc_mm_slot(void)
> -{
> -	if (!mm_slot_cache)	/* initialization failed */
> -		return NULL;
> -	return kmem_cache_zalloc(mm_slot_cache, GFP_KERNEL);
> -}
> -
> -static inline void free_mm_slot(struct mm_slot *mm_slot)
> -{
> -	kmem_cache_free(mm_slot_cache, mm_slot);
> -}
> -
> -static struct mm_slot *get_mm_slot(struct mm_struct *mm)
> -{
> -	struct mm_slot *mm_slot;
> -
> -	hash_for_each_possible(mm_slots_hash, mm_slot, hash, (unsigned long)mm)
> -		if (mm == mm_slot->mm)
> -			return mm_slot;
> -
> -	return NULL;
> -}
> -
> -static void insert_to_mm_slots_hash(struct mm_struct *mm,
> -				    struct mm_slot *mm_slot)
> -{
> -	mm_slot->mm = mm;
> -	hash_add(mm_slots_hash, &mm_slot->hash, (long)mm);
> -}
> -
>   static inline int hpage_collapse_test_exit(struct mm_struct *mm)
>   {
>   	return atomic_read(&mm->mm_users) == 0;
> @@ -450,28 +418,31 @@ static inline int hpage_collapse_test_exit(struct mm_struct *mm)
>   
>   void __khugepaged_enter(struct mm_struct *mm)
>   {
> -	struct mm_slot *mm_slot;
> +	struct khugepaged_mm_slot *mm_slot;
> +	struct mm_slot *slot;
>   	int wakeup;
>   
> -	mm_slot = alloc_mm_slot();
> +	mm_slot = mm_slot_alloc(mm_slot_cache);
>   	if (!mm_slot)
>   		return;
>   
> +	slot = &mm_slot->slot;
> +
>   	/* __khugepaged_exit() must not run from under us */
>   	VM_BUG_ON_MM(hpage_collapse_test_exit(mm), mm);
>   	if (unlikely(test_and_set_bit(MMF_VM_HUGEPAGE, &mm->flags))) {
> -		free_mm_slot(mm_slot);
> +		mm_slot_free(mm_slot_cache, mm_slot);
>   		return;
>   	}
>   
>   	spin_lock(&khugepaged_mm_lock);
> -	insert_to_mm_slots_hash(mm, mm_slot);
> +	mm_slot_insert(mm_slots_hash, mm, slot);
>   	/*
>   	 * Insert just behind the scanning cursor, to let the area settle
>   	 * down a little.
>   	 */
>   	wakeup = list_empty(&khugepaged_scan.mm_head);
> -	list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head);
> +	list_add_tail(&slot->mm_node, &khugepaged_scan.mm_head);
>   	spin_unlock(&khugepaged_mm_lock);
>   
>   	mmgrab(mm);
> @@ -491,21 +462,23 @@ void khugepaged_enter_vma(struct vm_area_struct *vma,
>   
>   void __khugepaged_exit(struct mm_struct *mm)
>   {
> -	struct mm_slot *mm_slot;
> +	struct khugepaged_mm_slot *mm_slot;
> +	struct mm_slot *slot;
>   	int free = 0;
>   
>   	spin_lock(&khugepaged_mm_lock);
> -	mm_slot = get_mm_slot(mm);
> +	slot = mm_slot_lookup(mm_slots_hash, mm);
> +	mm_slot = mm_slot_entry(slot, struct khugepaged_mm_slot, slot);
>   	if (mm_slot && khugepaged_scan.mm_slot != mm_slot) {
> -		hash_del(&mm_slot->hash);
> -		list_del(&mm_slot->mm_node);
> +		hash_del(&slot->hash);
> +		list_del(&slot->mm_node);
>   		free = 1;
>   	}
>   	spin_unlock(&khugepaged_mm_lock);
>   
>   	if (free) {
>   		clear_bit(MMF_VM_HUGEPAGE, &mm->flags);
> -		free_mm_slot(mm_slot);
> +		mm_slot_free(mm_slot_cache, mm_slot);
>   		mmdrop(mm);
>   	} else if (mm_slot) {
>   		/*
> @@ -1321,16 +1294,17 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm,
>   	return result;
>   }
>   
> -static void collect_mm_slot(struct mm_slot *mm_slot)
> +static void collect_mm_slot(struct khugepaged_mm_slot *mm_slot)
>   {
> -	struct mm_struct *mm = mm_slot->mm;
> +	struct mm_slot *slot = &mm_slot->slot;
> +	struct mm_struct *mm = slot->mm;
>   
>   	lockdep_assert_held(&khugepaged_mm_lock);
>   
>   	if (hpage_collapse_test_exit(mm)) {
>   		/* free mm_slot */
> -		hash_del(&mm_slot->hash);
> -		list_del(&mm_slot->mm_node);
> +		hash_del(&slot->hash);
> +		list_del(&slot->mm_node);
>   
>   		/*
>   		 * Not strictly needed because the mm exited already.
> @@ -1339,7 +1313,7 @@ static void collect_mm_slot(struct mm_slot *mm_slot)
>   		 */
>   
>   		/* khugepaged_mm_lock actually not necessary for the below */
> -		free_mm_slot(mm_slot);
> +		mm_slot_free(mm_slot_cache, mm_slot);
>   		mmdrop(mm);
>   	}
>   }
> @@ -1352,12 +1326,14 @@ static void collect_mm_slot(struct mm_slot *mm_slot)
>   static void khugepaged_add_pte_mapped_thp(struct mm_struct *mm,
>   					  unsigned long addr)
>   {
> -	struct mm_slot *mm_slot;
> +	struct khugepaged_mm_slot *mm_slot;
> +	struct mm_slot *slot;
>   
>   	VM_BUG_ON(addr & ~HPAGE_PMD_MASK);
>   
>   	spin_lock(&khugepaged_mm_lock);
> -	mm_slot = get_mm_slot(mm);
> +	slot = mm_slot_lookup(mm_slots_hash, mm);
> +	mm_slot = mm_slot_entry(slot, struct khugepaged_mm_slot, slot);
>   	if (likely(mm_slot && mm_slot->nr_pte_mapped_thp < MAX_PTE_MAPPED_THP))
>   		mm_slot->pte_mapped_thp[mm_slot->nr_pte_mapped_thp++] = addr;
>   	spin_unlock(&khugepaged_mm_lock);
> @@ -1489,9 +1465,10 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr)
>   	goto drop_hpage;
>   }
>   
> -static void khugepaged_collapse_pte_mapped_thps(struct mm_slot *mm_slot)
> +static void khugepaged_collapse_pte_mapped_thps(struct khugepaged_mm_slot *mm_slot)
>   {
> -	struct mm_struct *mm = mm_slot->mm;
> +	struct mm_slot *slot = &mm_slot->slot;
> +	struct mm_struct *mm = slot->mm;
>   	int i;
>   
>   	if (likely(mm_slot->nr_pte_mapped_thp == 0))
> @@ -2054,7 +2031,8 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
>   	__acquires(&khugepaged_mm_lock)
>   {
>   	struct vma_iterator vmi;
> -	struct mm_slot *mm_slot;
> +	struct khugepaged_mm_slot *mm_slot;
> +	struct mm_slot *slot;
>   	struct mm_struct *mm;
>   	struct vm_area_struct *vma;
>   	int progress = 0;
> @@ -2064,18 +2042,20 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
>   	lockdep_assert_held(&khugepaged_mm_lock);
>   	*result = SCAN_FAIL;
>   
> -	if (khugepaged_scan.mm_slot)
> +	if (khugepaged_scan.mm_slot) {
>   		mm_slot = khugepaged_scan.mm_slot;
> -	else {
> -		mm_slot = list_entry(khugepaged_scan.mm_head.next,
> +		slot = &mm_slot->slot;
> +	} else {
> +		slot = list_entry(khugepaged_scan.mm_head.next,
>   				     struct mm_slot, mm_node);
> +		mm_slot = mm_slot_entry(slot, struct khugepaged_mm_slot, slot);
>   		khugepaged_scan.address = 0;
>   		khugepaged_scan.mm_slot = mm_slot;
>   	}
>   	spin_unlock(&khugepaged_mm_lock);
>   	khugepaged_collapse_pte_mapped_thps(mm_slot);
>   
> -	mm = mm_slot->mm;
> +	mm = slot->mm;
>   	/*
>   	 * Don't wait for semaphore (to avoid long wait times).  Just move to
>   	 * the next mm on the list.
> @@ -2171,10 +2151,11 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result,
>   		 * khugepaged runs here, khugepaged_exit will find
>   		 * mm_slot not pointing to the exiting mm.
>   		 */
> -		if (mm_slot->mm_node.next != &khugepaged_scan.mm_head) {
> -			khugepaged_scan.mm_slot = list_entry(
> -				mm_slot->mm_node.next,
> -				struct mm_slot, mm_node);
> +		if (slot->mm_node.next != &khugepaged_scan.mm_head) {
> +			slot = list_entry(slot->mm_node.next,
> +					  struct mm_slot, mm_node);
> +			khugepaged_scan.mm_slot =
> +				mm_slot_entry(slot, struct khugepaged_mm_slot, slot);
>   			khugepaged_scan.address = 0;
>   		} else {
>   			khugepaged_scan.mm_slot = NULL;
> @@ -2269,7 +2250,7 @@ static void khugepaged_wait_work(void)
>   
>   static int khugepaged(void *none)
>   {
> -	struct mm_slot *mm_slot;
> +	struct khugepaged_mm_slot *mm_slot;
>   
>   	set_freezable();
>   	set_user_nice(current, MAX_NICE);

--
Thanks,
Qi