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Commit 4f231228 authored by Jens Axboe's avatar Jens Axboe
Browse files

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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 2b1ccc0e

fs/splice.c

+4 −6
Original line number Diff line number Diff line
@@ -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);