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Subject: Re: [f2fs-dev] [PATCH v2 1/2] f2fs: compress: introduce page array
 slab cache
From:   Chao Yu <yuchao0@huawei.com>
To:     Jaegeuk Kim <jaegeuk@kernel.org>
CC:     <linux-kernel@vger.kernel.org>,
        <linux-f2fs-devel@lists.sourceforge.net>
References: <20200914090514.50102-1-yuchao0@huawei.com>
 <20200929082306.GA1567825@google.com>
 <6e7639db-9120-d406-0a46-ec841845bb28@huawei.com>
 <20200929084739.GB1567825@google.com>
 <1b9774da-b2a8-2009-7796-9c576af1b4c4@huawei.com>
Message-ID: <5872f50c-4f3c-84bb-636f-6a6bd748c25f@huawei.com>
Date:   Tue, 29 Sep 2020 17:24:33 +0800
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On 2020/9/29 17:15, Chao Yu wrote:
> On 2020/9/29 16:47, Jaegeuk Kim wrote:
>> On 09/29, Chao Yu wrote:
>>> On 2020/9/29 16:23, Jaegeuk Kim wrote:
>>>> I found a bug related to the number of page pointer allocation related to
>>>> nr_cpages.
>>>
>>> Jaegeuk,
>>>
>>> If I didn't miss anything, you mean that nr_cpages could be larger
>>> than nr_rpages, right? the problematic case here is lzo/lzo-rle:
>>>
>>> cc->clen = lzo1x_worst_compress(PAGE_SIZE << cc->log_cluster_size);
>>>
>>> As we can't limited clen as we did for lz4/zstd:
>>>
>>> cc->clen = cc->rlen - PAGE_SIZE - COMPRESS_HEADER_SIZE;
>>
>> Yes, I've seen some memory corruption in lzo test. Here is another patch to fix
>> mem leak.
>>
>> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
>> ---
>>    fs/f2fs/compress.c | 67 ++++++++++++++++++++++++++++------------------
>>    1 file changed, 41 insertions(+), 26 deletions(-)
>>
>> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
>> index f086ac43ca825..ba2d4897744d8 100644
>> --- a/fs/f2fs/compress.c
>> +++ b/fs/f2fs/compress.c
>> @@ -20,22 +20,20 @@
>>    static struct kmem_cache *cic_entry_slab;
>>    static struct kmem_cache *dic_entry_slab;
>>    
>> -static void *page_array_alloc(struct inode *inode)
>> +static void *page_array_alloc(struct inode *inode, int nr)
>>    {
>>    	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>> -	unsigned int size = sizeof(struct page *) <<
>> -				F2FS_I(inode)->i_log_cluster_size;
>> +	unsigned int size = sizeof(struct page *) * nr;
>>    
>>    	if (likely(size == sbi->page_array_slab_size))
>>    		return kmem_cache_zalloc(sbi->page_array_slab, GFP_NOFS);
>>    	return f2fs_kzalloc(sbi, size, GFP_NOFS);
>>    }
>>    
>> -static void page_array_free(struct inode *inode, void *pages)
>> +static void page_array_free(struct inode *inode, void *pages, int nr)
>>    {
>>    	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
>> -	unsigned int size = sizeof(struct page *) <<
>> -				F2FS_I(inode)->i_log_cluster_size;
>> +	unsigned int size = sizeof(struct page *) * nr;
>>    
>>    	if (!pages)
>>    		return;
>> @@ -162,13 +160,13 @@ int f2fs_init_compress_ctx(struct compress_ctx *cc)
>>    	if (cc->rpages)
>>    		return 0;
>>    
>> -	cc->rpages = page_array_alloc(cc->inode);
>> +	cc->rpages = page_array_alloc(cc->inode, cc->cluster_size);
>>    	return cc->rpages ? 0 : -ENOMEM;
>>    }
>>    
>>    void f2fs_destroy_compress_ctx(struct compress_ctx *cc)
>>    {
>> -	page_array_free(cc->inode, cc->rpages);
>> +	page_array_free(cc->inode, cc->rpages, cc->cluster_size);
>>    	cc->rpages = NULL;
>>    	cc->nr_rpages = 0;
>>    	cc->nr_cpages = 0;
>> @@ -602,7 +600,8 @@ static int f2fs_compress_pages(struct compress_ctx *cc)
>>    	struct f2fs_inode_info *fi = F2FS_I(cc->inode);
>>    	const struct f2fs_compress_ops *cops =
>>    				f2fs_cops[fi->i_compress_algorithm];
>> -	unsigned int max_len, nr_cpages;
>> +	unsigned int max_len, new_nr_cpages;
>> +	struct page **new_cpages;
>>    	int i, ret;
>>    
>>    	trace_f2fs_compress_pages_start(cc->inode, cc->cluster_idx,
>> @@ -617,7 +616,7 @@ static int f2fs_compress_pages(struct compress_ctx *cc)
>>    	max_len = COMPRESS_HEADER_SIZE + cc->clen;
>>    	cc->nr_cpages = DIV_ROUND_UP(max_len, PAGE_SIZE);
>>    
>> -	cc->cpages = page_array_alloc(cc->inode);
>> +	cc->cpages = page_array_alloc(cc->inode, cc->nr_cpages);
> 
> Well, cc->nr_cpages will be set to cc->nr_rpages - 1 for zstd/lz4 cases, so
> this will make cpages allocation fallback to kmalloc, which can cause more
> memory use.

Could we handle cpages allocation for lzo/lzo-rle separately as:

force_xxx = is_lzo/lzo-rle_algorithm and is_cpages_array_allocation

page_array_alloc(, force_kmalloc)
page_array_free(, force_kfree)

Thanks,

> 
> Thanks,
> 
>>    	if (!cc->cpages) {
>>    		ret = -ENOMEM;
>>    		goto destroy_compress_ctx;
>> @@ -659,16 +658,28 @@ static int f2fs_compress_pages(struct compress_ctx *cc)
>>    	for (i = 0; i < COMPRESS_DATA_RESERVED_SIZE; i++)
>>    		cc->cbuf->reserved[i] = cpu_to_le32(0);
>>    
>> -	nr_cpages = DIV_ROUND_UP(cc->clen + COMPRESS_HEADER_SIZE, PAGE_SIZE);
>> +	new_nr_cpages = DIV_ROUND_UP(cc->clen + COMPRESS_HEADER_SIZE, PAGE_SIZE);
>> +
>> +	/* Now we're going to cut unnecessary tail pages */
>> +	new_cpages = page_array_alloc(cc->inode, new_nr_cpages);
>> +	if (new_cpages) {
>> +		ret = -ENOMEM;
>> +		goto out_vunmap_cbuf;
>> +	}
>>    
>>    	/* zero out any unused part of the last page */
>>    	memset(&cc->cbuf->cdata[cc->clen], 0,
>> -	       (nr_cpages * PAGE_SIZE) - (cc->clen + COMPRESS_HEADER_SIZE));
>> +			(new_nr_cpages * PAGE_SIZE) -
>> +			(cc->clen + COMPRESS_HEADER_SIZE));
>>    
>>    	vm_unmap_ram(cc->cbuf, cc->nr_cpages);
>>    	vm_unmap_ram(cc->rbuf, cc->cluster_size);
>>    
>> -	for (i = nr_cpages; i < cc->nr_cpages; i++) {
>> +	for (i = 0; i < cc->nr_cpages; i++) {
>> +		if (i < new_nr_cpages) {
>> +			new_cpages[i] = cc->cpages[i];
>> +			continue;
>> +		}
>>    		f2fs_compress_free_page(cc->cpages[i]);
>>    		cc->cpages[i] = NULL;
>>    	}
>> @@ -676,7 +687,9 @@ static int f2fs_compress_pages(struct compress_ctx *cc)
>>    	if (cops->destroy_compress_ctx)
>>    		cops->destroy_compress_ctx(cc);
>>    
>> -	cc->nr_cpages = nr_cpages;
>> +	page_array_free(cc->inode, cc->cpages, cc->nr_cpages);
>> +	cc->cpages = new_cpages;
>> +	cc->nr_cpages = new_nr_cpages;
>>    
>>    	trace_f2fs_compress_pages_end(cc->inode, cc->cluster_idx,
>>    							cc->clen, ret);
>> @@ -691,7 +704,7 @@ static int f2fs_compress_pages(struct compress_ctx *cc)
>>    		if (cc->cpages[i])
>>    			f2fs_compress_free_page(cc->cpages[i]);
>>    	}
>> -	page_array_free(cc->inode, cc->cpages);
>> +	page_array_free(cc->inode, cc->cpages, cc->nr_cpages);
>>    	cc->cpages = NULL;
>>    destroy_compress_ctx:
>>    	if (cops->destroy_compress_ctx)
>> @@ -730,7 +743,7 @@ void f2fs_decompress_pages(struct bio *bio, struct page *page, bool verity)
>>    		goto out_free_dic;
>>    	}
>>    
>> -	dic->tpages = page_array_alloc(dic->inode);
>> +	dic->tpages = page_array_alloc(dic->inode, dic->cluster_size);
>>    	if (!dic->tpages) {
>>    		ret = -ENOMEM;
>>    		goto out_free_dic;
>> @@ -1203,7 +1216,7 @@ static int f2fs_write_compressed_pages(struct compress_ctx *cc,
>>    	cic->magic = F2FS_COMPRESSED_PAGE_MAGIC;
>>    	cic->inode = inode;
>>    	atomic_set(&cic->pending_pages, cc->nr_cpages);
>> -	cic->rpages = page_array_alloc(cc->inode);
>> +	cic->rpages = page_array_alloc(cc->inode, cc->cluster_size);
>>    	if (!cic->rpages)
>>    		goto out_put_cic;
>>    
>> @@ -1297,11 +1310,13 @@ static int f2fs_write_compressed_pages(struct compress_ctx *cc,
>>    	spin_unlock(&fi->i_size_lock);
>>    
>>    	f2fs_put_rpages(cc);
>> +	page_array_free(cc->inode, cc->cpages, cc->nr_cpages);
>> +	cc->cpages = NULL;
>>    	f2fs_destroy_compress_ctx(cc);
>>    	return 0;
>>    
>>    out_destroy_crypt:
>> -	page_array_free(cc->inode, cic->rpages);
>> +	page_array_free(cc->inode, cic->rpages, cc->cluster_size);
>>    
>>    	for (--i; i >= 0; i--)
>>    		fscrypt_finalize_bounce_page(&cc->cpages[i]);
>> @@ -1310,6 +1325,8 @@ static int f2fs_write_compressed_pages(struct compress_ctx *cc,
>>    			continue;
>>    		f2fs_put_page(cc->cpages[i], 1);
>>    	}
>> +	page_array_free(cc->inode, cc->cpages, cc->nr_cpages);
>> +	cc->cpages = NULL;
>>    out_put_cic:
>>    	kmem_cache_free(cic_entry_slab, cic);
>>    out_put_dnode:
>> @@ -1345,7 +1362,7 @@ void f2fs_compress_write_end_io(struct bio *bio, struct page *page)
>>    		end_page_writeback(cic->rpages[i]);
>>    	}
>>    
>> -	page_array_free(cic->inode, cic->rpages);
>> +	page_array_free(cic->inode, cic->rpages, cic->nr_rpages);
>>    	kmem_cache_free(cic_entry_slab, cic);
>>    }
>>    
>> @@ -1442,8 +1459,6 @@ int f2fs_write_multi_pages(struct compress_ctx *cc,
>>    
>>    		err = f2fs_write_compressed_pages(cc, submitted,
>>    							wbc, io_type);
>> -		page_array_free(cc->inode, cc->cpages);
>> -		cc->cpages = NULL;
>>    		if (!err)
>>    			return 0;
>>    		f2fs_bug_on(F2FS_I_SB(cc->inode), err != -EAGAIN);
>> @@ -1468,7 +1483,7 @@ struct decompress_io_ctx *f2fs_alloc_dic(struct compress_ctx *cc)
>>    	if (!dic)
>>    		return ERR_PTR(-ENOMEM);
>>    
>> -	dic->rpages = page_array_alloc(cc->inode);
>> +	dic->rpages = page_array_alloc(cc->inode, cc->cluster_size);
>>    	if (!dic->rpages) {
>>    		kmem_cache_free(dic_entry_slab, dic);
>>    		return ERR_PTR(-ENOMEM);
>> @@ -1487,7 +1502,7 @@ struct decompress_io_ctx *f2fs_alloc_dic(struct compress_ctx *cc)
>>    		dic->rpages[i] = cc->rpages[i];
>>    	dic->nr_rpages = cc->cluster_size;
>>    
>> -	dic->cpages = page_array_alloc(dic->inode);
>> +	dic->cpages = page_array_alloc(dic->inode, dic->nr_cpages);
>>    	if (!dic->cpages)
>>    		goto out_free;
>>    
>> @@ -1522,7 +1537,7 @@ void f2fs_free_dic(struct decompress_io_ctx *dic)
>>    				continue;
>>    			f2fs_compress_free_page(dic->tpages[i]);
>>    		}
>> -		page_array_free(dic->inode, dic->tpages);
>> +		page_array_free(dic->inode, dic->tpages, dic->cluster_size);
>>    	}
>>    
>>    	if (dic->cpages) {
>> @@ -1531,10 +1546,10 @@ void f2fs_free_dic(struct decompress_io_ctx *dic)
>>    				continue;
>>    			f2fs_compress_free_page(dic->cpages[i]);
>>    		}
>> -		page_array_free(dic->inode, dic->cpages);
>> +		page_array_free(dic->inode, dic->cpages, dic->nr_cpages);
>>    	}
>>    
>> -	page_array_free(dic->inode, dic->rpages);
>> +	page_array_free(dic->inode, dic->rpages, dic->nr_rpages);
>>    	kmem_cache_free(dic_entry_slab, dic);
>>    }
>>    
>>
> 
> 
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