Messages in this thread Patch in this message |  | | From | Nick Piggin <> | Subject | [patch 5/9] mm: debug write deadlocks | Date | Sun, 4 Feb 2007 09:50:28 +0100 (CET) |
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Allow CONFIG_DEBUG_VM to switch off the prefaulting logic, to simulate the difficult race where the page may be unmapped before calling copy_from_user. 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>
Index: linux-2.6/mm/filemap.c =================================================================== --- linux-2.6.orig/mm/filemap.c +++ linux-2.6/mm/filemap.c @@ -2103,6 +2103,7 @@ generic_file_buffered_write(struct kiocb 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 @@ -2110,6 +2111,7 @@ generic_file_buffered_write(struct kiocb * up-to-date. */ fault_in_pages_readable(buf, maxlen); +#endif page = __grab_cache_page(mapping,index,&cached_page,&lru_pvec); if (!page) { - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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