From: Alan Stern <stern@rowland.harvard.edu>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: syzkaller <syzkaller@googlegroups.com>,
Andrey Konovalov <andreyknvl@google.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
USB list <linux-usb@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Kostya Serebryany <kcc@google.com>
Subject: Re: usb/core: warning in usb_create_ep_devs/sysfs_create_dir_ns
Date: Tue, 13 Dec 2016 13:38:26 -0500 (EST) [thread overview]
Message-ID: <Pine.LNX.4.44L0.1612131320350.1533-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <CACT4Y+ZTWzdefxQQy9hi1ZSQ=60TNi0+MF2D8VHC7FhWVd0oHg@mail.gmail.com>
On Tue, 13 Dec 2016, Dmitry Vyukov wrote:
> On Tue, Dec 13, 2016 at 4:52 PM, Alan Stern <stern@rowland.harvard.edu> wrote:
> > On Tue, 13 Dec 2016, Dmitry Vyukov wrote:
> >
> >> >> > If it is
> >> >> > not a bug in kernel source code, then it must not produce a WARNING.
> >> >
> >> > What about a memory allocation failure? The memory management part of
> >> > the kernel produces a WARNING message if an allocation fails and the
> >> > caller did not specify __GFP_NOWARN.
> >> >
> >> > There is no way for a driver to guarantee that a memory allocation
> >> > request will succeed -- failure is always an option. But obviously
> >> > memory allocation failures are not bugs in the kernel.
> >> >
> >> > Are you saying that mm/page_alloc.c:warn_alloc() should produce
> >> > something other than a WARNING?
> >>
> >>
> >> The main thing I am saying is that we absolutely need a way for a
> >> human or a computer program to be able to determine if there is
> >> anything wrong with kernel or not.
> > Doesn't it also produce a WARNING under other circumstances?
>
> No.
>
> OOM is not a WARNING and is easily distinguishable from BUG/WARNING.
> Memory allocator does not print WARNINGs on allocation failures.
Do you count dev_warn the same as WARN or WARN_ON? What about dev_WARN
or pr_warn() or printk(KERN_WARNING...)? Maybe we're not talking about
the same messages.
The USB subsystem has got tons of dev_warn() and dev_err() calls.
Relatively few (if any) of them are for kernel bugs.
Alan Stern
next prev parent reply other threads:[~2016-12-13 18:38 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-12 20:48 usb/core: warning in usb_create_ep_devs/sysfs_create_dir_ns Andrey Konovalov
2016-12-12 21:05 ` Alan Stern
2016-12-12 21:16 ` Dmitry Vyukov
2016-12-12 21:48 ` Alan Stern
2016-12-12 22:04 ` Alan Stern
2016-12-13 15:07 ` Dmitry Vyukov
2016-12-13 15:52 ` Alan Stern
2016-12-13 16:23 ` Dmitry Vyukov
2016-12-13 18:38 ` Alan Stern [this message]
2016-12-13 18:44 ` Dmitry Vyukov
2016-12-13 20:09 ` Alan Stern
2016-12-13 20:32 ` Dmitry Vyukov
2016-12-12 21:49 ` Greg Kroah-Hartman
2016-12-16 18:01 ` Alan Stern
2016-12-17 17:12 ` Andrey Konovalov
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