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Date:   Wed, 14 Nov 2018 17:06:01 +0100
From:   Oleg Nesterov <oleg@redhat.com>
To:     Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc:     srikar@linux.vnet.ibm.com, rostedt@goodmis.org,
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Subject: Re: [PATCH] Uprobes: Fix kernel oops with delayed_uprobe_remove()
Message-ID: <20181114160600.GD13885@redhat.com>
References: <20181114081921.26484-1-ravi.bangoria@linux.ibm.com>
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On 11/14, Ravi Bangoria wrote:
>
> syzbot reported a kernel crash with delayed_uprobe_remove():
>   https://lkml.org/lkml/2018/11/1/1244
>
> Backtrace mentioned in the link points to a race between process
> exit and uprobe_unregister(). Fix it by locking delayed_uprobe_lock
> before calling delayed_uprobe_remove() from put_uprobe().

The patch looks good to me, but could you update the changelog?

Please explain that the exiting task calls uprobe_clear_state() which
can race with delayed_uprobe_remove(). IIUC this is the only problem
solved by this patch, right?

Oleg.