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Commit 5fe17237 authored Oct 16, 2007 by Nick Piggin Committed by Linus Torvalds Oct 16, 2007

mm: debug write deadlocks



Allow CONFIG_DEBUG_VM to switch off the prefaulting logic, to simulate the
Makes the race much easier to hit.

This is useful for demonstration and testing purposes, but is removed in a
subsequent patch.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent ae37461c

mm/filemap.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -1878,6 +1878,7 @@ generic_file_buffered_write(struct kiocb iocb, const struct iovec iov,
		if (maxlen > bytes)
		maxlen = bytes;

		#ifndef CONFIG_DEBUG_VM
		/*
		* Bring in the user page that we will copy from _first_.
		* Otherwise there's a nasty deadlock on copying from the
		@@ -1885,6 +1886,7 @@ generic_file_buffered_write(struct kiocb iocb, const struct iovec iov,
		* up-to-date.
		*/
		fault_in_pages_readable(buf, maxlen);
		#endif

		page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec);
		if (!page) {