Re: 2.6.16-rc6-mm2

Christoph Lameter
2006-06-12T22:16:44Z

On Mon, 12 Jun 2006, Cedric Le Goater wrote:

> Unable to handle kernel NULL pointer dereference at 0000000000000007 RIP:
> [<ffffffff8025b017>] dec_zone_page_state+0x1/0x5b

Seems that req->wb_page may be NULL.

This patch may fix it but we may miss an unstable page then. We may
have to move the decrement of NR_UNSTABLE to a different location when
wb_page is still valid.

Index: linux-2.6.17-rc6-cl/fs/nfs/write.c
===================================================================
--- linux-2.6.17-rc6-cl.orig/fs/nfs/write.c 2006-06-12 13:37:47.321243148 -0700
+++ linux-2.6.17-rc6-cl/fs/nfs/write.c 2006-06-12 15:13:48.020908204 -0700
@@ -1419,7 +1419,8 @@ static void nfs_commit_done(struct rpc_t
nfs_mark_request_dirty(req);
next:
nfs_clear_page_writeback(req);
- dec_zone_page_state(req->wb_page, NR_UNSTABLE);
+ if (req->wb_page)
+ dec_zone_page_state(req->wb_page, NR_UNSTABLE);
}
}