[Ocfs2-devel] [PATCH] ocfs2: Fix deadlock when allocating page

[Sunil Mushran]

Thanks. I think we have few open bugzillas for this issue.

On Aug 24, 2010, at 5:28 AM, Jan Kara <jack at suse.cz> wrote:

> We cannot call grab_cache_page() when holding filesystem locks or with
> a transaction started as grab_cache_page() calls page allocation with
> GFP_KERNEL flag and thus page reclaim can recurse back into the filesystem
> causing deadlocks or various assertion failures. We have to use
> find_or_create_page() instead and pass it GFP_NOFS as we do with other
> allocations.
> 
> Signed-off-by: Jan Kara <jack at suse.cz>
> ---
> fs/ocfs2/alloc.c        |    2 +-
> fs/ocfs2/file.c         |    2 +-
> fs/ocfs2/refcounttree.c |    5 +++--
> 3 files changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
> index 215e12c..592fae5 100644
> --- a/fs/ocfs2/alloc.c
> +++ b/fs/ocfs2/alloc.c
> @@ -6672,7 +6672,7 @@ int ocfs2_grab_pages(struct inode *inode, loff_t start, loff_t end,
>    last_page_bytes = PAGE_ALIGN(end);
>    index = start >> PAGE_CACHE_SHIFT;
>    do {
> -        pages[numpages] = grab_cache_page(mapping, index);
> +        pages[numpages] = find_or_create_page(mapping, index, GFP_NOFS);
>        if (!pages[numpages]) {
>            ret = -ENOMEM;
>            mlog_errno(ret);
> diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
> index 81296b4..b28cce8 100644
> --- a/fs/ocfs2/file.c
> +++ b/fs/ocfs2/file.c
> @@ -774,7 +774,7 @@ static int ocfs2_write_zero_page(struct inode *inode, u64 abs_from,
>    BUG_ON(abs_to > (((u64)index + 1) << PAGE_CACHE_SHIFT));
>    BUG_ON(abs_from & (inode->i_blkbits - 1));
> 
> -    page = grab_cache_page(mapping, index);
> +    page = find_or_create_page(mapping, index, GFP_NOFS);
>    if (!page) {
>        ret = -ENOMEM;
>        mlog_errno(ret);
> diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
> index 73a11cc..0afeda8 100644
> --- a/fs/ocfs2/refcounttree.c
> +++ b/fs/ocfs2/refcounttree.c
> @@ -2960,7 +2960,7 @@ static int ocfs2_duplicate_clusters_by_page(handle_t *handle,
>        if (map_end & (PAGE_CACHE_SIZE - 1))
>            to = map_end & (PAGE_CACHE_SIZE - 1);
> 
> -        page = grab_cache_page(mapping, page_index);
> +        page = find_or_create_page(mapping, page_index, GFP_NOFS);
> 
>        /*
>         * In case PAGE_CACHE_SIZE <= CLUSTER_SIZE, This page
> @@ -3179,7 +3179,8 @@ static int ocfs2_cow_sync_writeback(struct super_block *sb,
>        if (map_end > end)
>            map_end = end;
> 
> -        page = grab_cache_page(context->inode->i_mapping, page_index);
> +        page = find_or_create_page(context->inode->i_mapping,
> +                       page_index, GFP_NOFS);
>        BUG_ON(!page);
> 
>        wait_on_page_writeback(page);
> -- 
> 1.6.4.2
> 
> 
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