On Wed, 3 Sep 2008 23:01:29 -0700 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> I'll see if I cen reproduce the bug I'm
> actually tring to find with E100=n.
OK, this regression[*] bisects down to
commit b689ad2b010f09626a6158e1213a075a1aa9f299
Author: Alan Cox <alan@xxxxxxxxxx>
Date: Wed Sep 3 10:12:18 2008 +1000
tty-kref-get-current-tty
We now return a kref covered tty reference. That ensures the tty structure
doesn't go away when you have a return from get_current_tty. This is not
enough to protect you from most of the resources being freed behind your
back - yet.
This got a bit ugly, because tty-kref-get-current-tty fixes a pile of
compilation errors which were introduced in the innediately preceding
patch (tty-kref-modcount, I think). I roughly fixed those up by hand:
--- a/drivers/char/tty_io.c~b
+++ a/drivers/char/tty_io.c
@@ -1283,7 +1283,7 @@ static int init_dev(struct tty_driver *d
o_tty = alloc_tty_struct();
if (!o_tty)
goto free_mem_out;
- if (!try_module_get(driver->other)) {
+ if (!try_module_get(driver->owner)) {
/* This cannot in fact currently happen */
free_tty_struct(o_tty);
o_tty = NULL;
@@ -1408,7 +1408,7 @@ end_init:
free_mem_out:
kfree(o_tp);
if (o_tty) {
- module_put(o_tty->driver);
+ module_put(o_tty->driver->owner);
free_tty_struct(o_tty);
}
kfree(ltp);
@@ -1469,7 +1469,7 @@ static void release_one_tty(struct kref
tty->magic = 0;
/* FIXME: locking on tty->driver->refcount */
tty->driver->refcount--;
- module_put(driver->owner);
+ module_put(tty->driver->owner);
file_list_lock();
list_del_init(&tty->tty_files);
_
I cannot find any of these patches on a mailing list.
I cannot revert tty-kref-get-current-tty and I can't immediately spot
the bug in it.
I could revert the whole tty tree, but I'd prefer that you do it,
please. I've been trying for two days to get a -mm out, but I'm
building on a foundation of straw :(
[*] symptoms: there are no login prompts appearing on the VT consoles.
sshd works OK (will it did, but I had to disable the net driver due to
networking bisect breakage).
config: http://userweb.kernel.org/~akpm/config-sony.txt
dmesg: http://userweb.kernel.org/~akpm/dmesg-sony-2.txt
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