From 4f23122858a27ba97444b9b37a066d83edebd4c8 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 13 May 2009 08:35:35 +0200 Subject: [PATCH] splice: fix repeated kmap()'s in default_file_splice_read() We cannot reliably map more than one page at the time, or we risk deadlocking. Just allocate the pages from low mem instead. Reported-by: Andrew Morton Signed-off-by: Jens Axboe --- fs/splice.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/fs/splice.c b/fs/splice.c index eefd96b1d7fb..c5e3c79b95a8 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -580,13 +580,13 @@ ssize_t default_file_splice_read(struct file *in, loff_t *ppos, for (i = 0; i < nr_pages && i < PIPE_BUFFERS && len; i++) { struct page *page; - page = alloc_page(GFP_HIGHUSER); + page = alloc_page(GFP_USER); error = -ENOMEM; if (!page) goto err; this_len = min_t(size_t, len, PAGE_CACHE_SIZE - offset); - vec[i].iov_base = (void __user *) kmap(page); + vec[i].iov_base = (void __user *) page_address(page); vec[i].iov_len = this_len; pages[i] = page; spd.nr_pages++; @@ -604,7 +604,6 @@ ssize_t default_file_splice_read(struct file *in, loff_t *ppos, nr_freed = 0; for (i = 0; i < spd.nr_pages; i++) { - kunmap(pages[i]); this_len = min_t(size_t, vec[i].iov_len, res); partial[i].offset = 0; partial[i].len = this_len; @@ -624,10 +623,9 @@ ssize_t default_file_splice_read(struct file *in, loff_t *ppos, return res; err: - for (i = 0; i < spd.nr_pages; i++) { - kunmap(pages[i]); + for (i = 0; i < spd.nr_pages; i++) __free_page(pages[i]); - } + return error; } EXPORT_SYMBOL(default_file_splice_read); -- 2.25.1