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Commit 4595ef88 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds
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shmem: make shmem_inode_info::lock irq-safe 

We are going to need to call shmem_charge() under tree_lock to get
accoutning right on collapse of small tmpfs pages into a huge one.

The problem is that tree_lock is irq-safe and lockdep is not happy, that
we take irq-unsafe lock under irq-safe[1].

Let's convert the lock to irq-safe.

[1] https://gist.github.com/kiryl/80c0149e03ed35dfaf26628b8e03cdbc

Link: http://lkml.kernel.org/r/1466021202-61880-34-git-send-email-kirill.shutemov@linux.intel.com


Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 988ddb71

ipc/shm.c

+2 −2
Original line number Diff line number Diff line
@@ -766,10 +766,10 @@ static void shm_add_rss_swap(struct shmid_kernel *shp, 
	} else {

#ifdef CONFIG_SHMEM

		struct shmem_inode_info *info = SHMEM_I(inode);

		spin_lock(&info->lock);

		spin_lock_irq(&info->lock);

		*rss_add += inode->i_mapping->nrpages;

		*swp_add += info->swapped;

		spin_unlock(&info->lock);

		spin_unlock_irq(&info->lock);

#else

		*rss_add += inode->i_mapping->nrpages;

#endif

mm/shmem.c

+26 −24
Original line number Diff line number Diff line
@@ -258,14 +258,15 @@ bool shmem_charge(struct inode *inode, long pages) 
{

	struct shmem_inode_info *info = SHMEM_I(inode);

	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);

	unsigned long flags;



	if (shmem_acct_block(info->flags, pages))

		return false;

	spin_lock(&info->lock);

	spin_lock_irqsave(&info->lock, flags);

	info->alloced += pages;

	inode->i_blocks += pages * BLOCKS_PER_PAGE;

	shmem_recalc_inode(inode);

	spin_unlock(&info->lock);

	spin_unlock_irqrestore(&info->lock, flags);

	inode->i_mapping->nrpages += pages;



	if (!sbinfo->max_blocks)
@@ -273,10 +274,10 @@ bool shmem_charge(struct inode *inode, long pages) 
	if (percpu_counter_compare(&sbinfo->used_blocks,

				sbinfo->max_blocks - pages) > 0) {

		inode->i_mapping->nrpages -= pages;

		spin_lock(&info->lock);

		spin_lock_irqsave(&info->lock, flags);

		info->alloced -= pages;

		shmem_recalc_inode(inode);

		spin_unlock(&info->lock);

		spin_unlock_irqrestore(&info->lock, flags);



		return false;

	}
@@ -288,12 +289,13 @@ void shmem_uncharge(struct inode *inode, long pages) 
{

	struct shmem_inode_info *info = SHMEM_I(inode);

	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);

	unsigned long flags;



	spin_lock(&info->lock);

	spin_lock_irqsave(&info->lock, flags);

	info->alloced -= pages;

	inode->i_blocks -= pages * BLOCKS_PER_PAGE;

	shmem_recalc_inode(inode);

	spin_unlock(&info->lock);

	spin_unlock_irqrestore(&info->lock, flags);



	if (sbinfo->max_blocks)

		percpu_counter_sub(&sbinfo->used_blocks, pages);
@@ -818,10 +820,10 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend, 
		index++;

	}



	spin_lock(&info->lock);

	spin_lock_irq(&info->lock);

	info->swapped -= nr_swaps_freed;

	shmem_recalc_inode(inode);

	spin_unlock(&info->lock);

	spin_unlock_irq(&info->lock);

}



void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
@@ -838,9 +840,9 @@ static int shmem_getattr(struct vfsmount *mnt, struct dentry *dentry, 
	struct shmem_inode_info *info = SHMEM_I(inode);



	if (info->alloced - info->swapped != inode->i_mapping->nrpages) {

		spin_lock(&info->lock);

		spin_lock_irq(&info->lock);

		shmem_recalc_inode(inode);

		spin_unlock(&info->lock);

		spin_unlock_irq(&info->lock);

	}

	generic_fillattr(inode, stat);

	return 0;
@@ -984,9 +986,9 @@ static int shmem_unuse_inode(struct shmem_inode_info *info, 
		delete_from_swap_cache(*pagep);

		set_page_dirty(*pagep);

		if (!error) {

			spin_lock(&info->lock);

			spin_lock_irq(&info->lock);

			info->swapped--;

			spin_unlock(&info->lock);

			spin_unlock_irq(&info->lock);

			swap_free(swap);

		}

	}
@@ -1134,10 +1136,10 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) 
		list_add_tail(&info->swaplist, &shmem_swaplist);



	if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {

		spin_lock(&info->lock);

		spin_lock_irq(&info->lock);

		shmem_recalc_inode(inode);

		info->swapped++;

		spin_unlock(&info->lock);

		spin_unlock_irq(&info->lock);



		swap_shmem_alloc(swap);

		shmem_delete_from_page_cache(page, swp_to_radix_entry(swap));
@@ -1523,10 +1525,10 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, 


		mem_cgroup_commit_charge(page, memcg, true, false);



		spin_lock(&info->lock);

		spin_lock_irq(&info->lock);

		info->swapped--;

		shmem_recalc_inode(inode);

		spin_unlock(&info->lock);

		spin_unlock_irq(&info->lock);



		if (sgp == SGP_WRITE)

			mark_page_accessed(page);
@@ -1603,11 +1605,11 @@ alloc_nohuge: page = shmem_alloc_and_acct_page(gfp, info, sbinfo, 
				PageTransHuge(page));

		lru_cache_add_anon(page);



		spin_lock(&info->lock);

		spin_lock_irq(&info->lock);

		info->alloced += 1 << compound_order(page);

		inode->i_blocks += BLOCKS_PER_PAGE << compound_order(page);

		shmem_recalc_inode(inode);

		spin_unlock(&info->lock);

		spin_unlock_irq(&info->lock);

		alloced = true;



		/*
@@ -1639,9 +1641,9 @@ alloc_nohuge: page = shmem_alloc_and_acct_page(gfp, info, sbinfo, 
		if (alloced) {

			ClearPageDirty(page);

			delete_from_page_cache(page);

			spin_lock(&info->lock);

			spin_lock_irq(&info->lock);

			shmem_recalc_inode(inode);

			spin_unlock(&info->lock);

			spin_unlock_irq(&info->lock);

		}

		error = -EINVAL;

		goto unlock;
@@ -1673,9 +1675,9 @@ alloc_nohuge: page = shmem_alloc_and_acct_page(gfp, info, sbinfo, 
	}

	if (error == -ENOSPC && !once++) {

		info = SHMEM_I(inode);

		spin_lock(&info->lock);

		spin_lock_irq(&info->lock);

		shmem_recalc_inode(inode);

		spin_unlock(&info->lock);

		spin_unlock_irq(&info->lock);

		goto repeat;

	}

	if (error == -EEXIST)	/* from above or from radix_tree_insert */
@@ -1874,7 +1876,7 @@ int shmem_lock(struct file *file, int lock, struct user_struct *user) 
	struct shmem_inode_info *info = SHMEM_I(inode);

	int retval = -ENOMEM;



	spin_lock(&info->lock);

	spin_lock_irq(&info->lock);

	if (lock && !(info->flags & VM_LOCKED)) {

		if (!user_shm_lock(inode->i_size, user))

			goto out_nomem;
@@ -1889,7 +1891,7 @@ int shmem_lock(struct file *file, int lock, struct user_struct *user) 
	retval = 0;



out_nomem:

	spin_unlock(&info->lock);

	spin_unlock_irq(&info->lock);

	return retval;

}