From: Linus Torvalds <torvalds@linux-foundation.org>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Huangpeng (Peter)" <peter.huangpeng@huawei.com>,
qemu-devel@nongnu.org, Paolo Bonzini <pbonzini@redhat.com>,
Pavel Emelyanov <xemul@parallels.com>,
Hugh Dickins <hughd@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Andres Lagar-Cavilla <andreslc@google.com>,
Andy Lutomirski <luto@amacapital.net>,
linux-mm@kvack.org, "Kirill A. Shutemov" <kirill@shutemov.name>,
Rik van Riel <riel@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
linux-kernel@vger.kernel.org,
Sanidhya Kashyap <sanidhya.gatech@gmail.com>,
zhang.zhanghailiang@huawei.com,
Dave Hansen <dave.hansen@intel.com>, Mel Gorman <mgorman@suse.de>,
Peter Feiner <pfeiner@google.com>,
kvm@vger.kernel.org
Subject: Re: [PATCH 1/7] userfaultfd: require UFFDIO_API before other ioctls
Date: Mon, 15 Jun 2015 11:55:38 -1000 [thread overview]
Message-ID: <CA+55aFxKz5eONz1g57ccZ8b=6ivouQOapBtVjt7U3aOtrRgw8Q@mail.gmail.com> (raw)
In-Reply-To: <20150615214338.GH18909@redhat.com>
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On Jun 15, 2015 11:43 AM, "Andrea Arcangeli" <aarcange@redhat.com> wrote:
>
> Several times I got very hardly reproducible bugs noticed purely
> because of BUG_ON (not VM_BUG_ON)
Feel free to use them while developing. Don't send me patches with your
broken debug code, though.
For users, a dead machine means that it is less likely you will ever get a
bug report. People set "reboot on oops", and when running X is not always
something that can be seen anyway. They'll just see a rebooting or a dead
machine, and not send you any debug output.
This is not negotiable. Seriously. Get rid of the BUG_ON if you expect your
patches to be merged mainline.
Also, even for debugging, using something like
if (WARN_ON_ONCE(...))
return -EINVAL;
is the right thing to do. Then you can unwind locks etc, and return
cleanly, and you'll only get one warning rather than a stream of them etc.
So stop making excuses for your bad BUG_ON use. Do it in private where
nobody can see your perversions, or do it right.
Linus
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next prev parent reply other threads:[~2015-06-15 21:55 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-15 17:22 [PATCH 0/7] userfault21 update Andrea Arcangeli
2015-06-15 17:22 ` [PATCH 1/7] userfaultfd: require UFFDIO_API before other ioctls Andrea Arcangeli
2015-06-15 18:11 ` Linus Torvalds
2015-06-15 21:43 ` Andrea Arcangeli
2015-06-15 21:55 ` Linus Torvalds [this message]
2015-06-15 17:22 ` [PATCH 2/7] userfaultfd: propagate the full address in THP faults Andrea Arcangeli
2015-06-15 17:22 ` [PATCH 3/7] userfaultfd: allow signals to interrupt a userfault Andrea Arcangeli
2015-06-15 17:22 ` [PATCH 4/7] userfaultfd: avoid missing wakeups during refile in userfaultfd_read Andrea Arcangeli
2015-06-15 17:22 ` [PATCH 5/7] userfaultfd: switch to exclusive wakeup for blocking reads Andrea Arcangeli
2015-06-15 18:19 ` Linus Torvalds
2015-06-15 22:19 ` Andrea Arcangeli
2015-06-16 6:41 ` Linus Torvalds
2015-06-16 12:17 ` Andrea Arcangeli
2015-06-15 17:22 ` [PATCH 6/7] userfaultfd: Revert "userfaultfd: waitqueue: add nr wake parameter to __wake_up_locked_key" Andrea Arcangeli
2015-06-15 17:22 ` [PATCH 7/7] userfaultfd: selftest Andrea Arcangeli
2015-10-12 15:04 ` [PATCH 0/7] userfault21 update Patrick Donnelly
2015-10-19 21:42 ` Andrea Arcangeli
2015-10-20 13:44 ` Patrick Donnelly
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