linux-kernel - Kernel boot hangs on commit "switch fput to task_work

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20120710141830.GA5385@localhost>
Date:	Tue, 10 Jul 2012 22:18:30 +0800
From:	wfg@...ux.intel.com
To:	Al Viro <viro@...iv.linux.org.uk>
Cc:	linux-fsdevel@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Kernel boot hangs on commit "switch fput to task_work_add"

Hi Al,

The linux-next kernel reliably hung after this line:

[    4.846260] debug: unmapping init [mem 0xffff88000182a000-0xffff8800019fffff]

And it's bisected to commit:

        commit 4a9ffe81385c2af04f296bea05482f34e02ea10d
        Author: Al Viro <viro@...iv.linux.org.uk>
        Date:   Sun Jun 24 09:56:45 2012 +0400

            switch fput to task_work_add

            ... and schedule_work() for interrupt/kernel_thread callers
            (and yes, now it *is* OK to call from interrupt).

I tried add this debug aid:

init_post(void):
+       printk(KERN_WARNING "flush_delayed_fput\n");
        flush_delayed_fput();
+       printk(KERN_WARNING "flush_delayed_fput done\n");

And then it hangs after "flush_delayed_fput done". So it's not directly
freezing inside flush_delayed_fput()..

Thanks,
Fengguang

Download attachment "dmesg-kvm-fat-1642-2012-07-10-18-18-02" of type "application/octet-stream" (49859 bytes)

View attachment "config-3.5.0-rc6-07761-g46a7146" of type "text/plain" (50742 bytes)