Commit 68dfec3b authored by Chen Wandun's avatar Chen Wandun Committed by Zheng Zengkai
Browse files

mm/swapfile: use new way to fix broken kabi in swap_info_struct 

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I645JI



-------------------------------

Commit 46d673d7 ("mm/swapfile: fix broken kabi in swap_info_struct")
uses KABI_EXTEND to fix kabi broken problem, but this is not the safest
way, so use new way to fix this prolem.

Introduce new struct swap_extend_info that contains extend info of swap,
meanwhile use KABI_USE to repalce memory space reserved by KABI_RESERVER.

Signed-off-by: default avatarChen Wandun <chenwandun@huawei.com>
Reviewed-by: default avatarzhangjialin <zhangjialin11@huawei.com>
Reviewed-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parent 5d934d94

include/linux/swap.h

+7 −4
Original line number Diff line number Diff line
@@ -246,6 +246,11 @@ struct swap_cluster_list { 
	struct swap_cluster_info tail;

};



struct swap_extend_info {

	struct percpu_ref users;	/* indicate and keep swap device valid. */

	struct completion comp;		/* seldom referenced */

};



/*

 * The in-memory structure used to track swap areas.

 */
@@ -293,10 +298,8 @@ struct swap_info_struct { 
					 */

	struct work_struct discard_work; /* discard worker */

	struct swap_cluster_list discard_clusters; /* discard clusters list */

	KABI_RESERVE(1)

	KABI_USE(1, struct swap_extend_info *sei)

	KABI_RESERVE(2)

	KABI_EXTEND(struct percpu_ref users)	/* indicate and keep swap device valid. */

	KABI_EXTEND(struct completion comp)	/* seldom referenced */

	struct plist_node avail_lists[]; /*

					   * entries in swap_avail_heads, one

					   * entry per node.
@@ -537,7 +540,7 @@ sector_t swap_page_sector(struct page *page); 


static inline void put_swap_device(struct swap_info_struct *si)

{

	percpu_ref_put(&si->users);

	percpu_ref_put(&si->sei->users);

}



#else /* CONFIG_SWAP */

mm/swapfile.c

+21 −12
Original line number Diff line number Diff line
@@ -515,10 +515,10 @@ static void swap_discard_work(struct work_struct *work) 


static void swap_users_ref_free(struct percpu_ref *ref)

{

	struct swap_info_struct *si;

	struct swap_extend_info *sei;



	si = container_of(ref, struct swap_info_struct, users);

	complete(&si->comp);

	sei = container_of(ref, struct swap_extend_info, users);

	complete(&sei->comp);

}



static void alloc_cluster(struct swap_info_struct *si, unsigned long idx)
@@ -1316,7 +1316,7 @@ struct swap_info_struct *get_swap_device(swp_entry_t entry) 
	si = swp_swap_info(entry);

	if (!si)

		goto bad_nofile;

	if (!percpu_ref_tryget_live(&si->users))

	if (!percpu_ref_tryget_live(&si->sei->users))

		goto out;

	/*

	 * Guarantee the si->users are checked before accessing other
@@ -1336,7 +1336,7 @@ struct swap_info_struct *get_swap_device(swp_entry_t entry) 
out:

	return NULL;

put_out:

	percpu_ref_put(&si->users);

	percpu_ref_put(&si->sei->users);

	return NULL;

}
@@ -2542,7 +2542,7 @@ static void enable_swap_info(struct swap_info_struct *p, int prio, 
	/*

	 * Finished initializing swap device, now it's safe to reference it.

	 */

	percpu_ref_resurrect(&p->users);

	percpu_ref_resurrect(&p->sei->users);

	spin_lock(&swap_lock);

	spin_lock(&p->lock);

	_enable_swap_info(p);
@@ -2665,9 +2665,9 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) 
	 * We need synchronize_rcu() here to protect the accessing to

	 * the swap cache data structure.

	 */

	percpu_ref_kill(&p->users);

	percpu_ref_kill(&p->sei->users);

	synchronize_rcu();

	wait_for_completion(&p->comp);

	wait_for_completion(&p->sei->comp);



	flush_work(&p->discard_work);
@@ -2899,8 +2899,15 @@ static struct swap_info_struct *alloc_swap_info(void) 
	if (!p)

		return ERR_PTR(-ENOMEM);



	if (percpu_ref_init(&p->users, swap_users_ref_free,

	p->sei = kvzalloc(sizeof(struct swap_extend_info), GFP_KERNEL);

	if (!p->sei) {

		kvfree(p);

		return ERR_PTR(-ENOMEM);

	}



	if (percpu_ref_init(&p->sei->users, swap_users_ref_free,

			    PERCPU_REF_INIT_DEAD, GFP_KERNEL)) {

		kvfree(p->sei);

		kvfree(p);

		return ERR_PTR(-ENOMEM);

	}
@@ -2912,7 +2919,8 @@ static struct swap_info_struct *alloc_swap_info(void) 
	}

	if (type >= MAX_SWAPFILES) {

		spin_unlock(&swap_lock);

		percpu_ref_exit(&p->users);

		percpu_ref_exit(&p->sei->users);

		kvfree(p->sei);

		kvfree(p);

		return ERR_PTR(-EPERM);

	}
@@ -2941,12 +2949,13 @@ static struct swap_info_struct *alloc_swap_info(void) 
	p->flags = SWP_USED;

	spin_unlock(&swap_lock);

	if (defer) {

		percpu_ref_exit(&defer->users);

		percpu_ref_exit(&defer->sei->users);

		kvfree(defer->sei);

		kvfree(defer);

	}

	spin_lock_init(&p->lock);

	spin_lock_init(&p->cont_lock);

	init_completion(&p->comp);

	init_completion(&p->sei->comp);



	return p;

}