From: Vladimir V. Saveliev Date: Tue, 27 Jun 2006 09:53:57 +0000 (-0700) Subject: [PATCH] generic_file_buffered_write(): deadlock on vectored write X-Git-Tag: v2.6.18-rc1~554 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6527c2bdf1f833cc18e8f42bd97973d583e4aa83;p=pandora-kernel.git [PATCH] generic_file_buffered_write(): deadlock on vectored write generic_file_buffered_write() prefaults in user pages in order to avoid deadlock on copying from the same page as write goes to. However, it looks like there is a problem when write is vectored: fault_in_pages_readable brings in current segment or its part (maxlen). OTOH, filemap_copy_from_user_iovec is called to copy number of bytes (bytes) which may exceed current segment, so filemap_copy_from_user_iovec switches to the next segment which is not brought in yet. Pagefault is generated. That causes the deadlock if pagefault is for the same page write goes to: page being written is locked and not uptodate, pagefault will deadlock trying to lock locked page. [akpm@osdl.org: somewhat rewritten] Cc: Neil Brown Cc: Martin Schwidefsky Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed