Re: [bisect] NFS regression breaks X

From: Linus Torvalds
Date: Wed May 09 2007 - 18:10:44 EST




On Wed, 9 May 2007, Jeff Garzik wrote:
>
> I love bisect :)

Yeah, me too.

> bisect has identified the following commit as the one that
> causes my GNOME login to die, within 10 seconds of logging in:
>
> commit 2bea90d43a050bbc4021d44e59beb34f384438db

Ok, that commit looks nice in many ways, so I'd be loathe to revert it
entirely.

Can you try it with this patch that re-introduces the "total overkill"
slack calculations, and probably makes them even worse (there's a few
left-shifts added, and now it will left-shift the extra slacktoo).

But there are also some unexplained changes in that patch, so maybe the
size allocation isn't the big problem. For example, now "call_allocate()"
will set task->tk_status to zero which is totally strange.

But if it's the allocation that is too small, this patch may help.

Trond, Chuck?

Linus

--
net/sunrpc/clnt.c | 7 ++++++-
1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index d8fbee4..5b78692 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -738,6 +738,8 @@ call_reserveresult(struct rpc_task *task)
rpc_exit(task, status);
}

+#define RPC_SLACK_SPACE (1024u) /* apparently NOT total overkill */
+
/*
* 2. Allocate the buffer. For details, see sched.c:rpc_malloc.
* (Note: buffer memory is freed in xprt_release).
@@ -745,7 +747,7 @@ call_reserveresult(struct rpc_task *task)
static void
call_allocate(struct rpc_task *task)
{
- unsigned int slack = task->tk_auth->au_cslack;
+ unsigned int slack;
struct rpc_rqst *req = task->tk_rqstp;
struct rpc_xprt *xprt = task->tk_xprt;
struct rpc_procinfo *proc = task->tk_msg.rpc_proc;
@@ -764,6 +766,9 @@ call_allocate(struct rpc_task *task)
BUG_ON(proc->p_replen == 0);
}

+ /* Apparently not total overkill */
+ slack = max(task->tk_auth->au_cslack, RPC_SLACK_SPACE);
+
/*
* Calculate the size (in quads) of the RPC call
* and reply headers, and convert both values
-
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