Messages in this thread | | | Date | Mon, 22 May 2023 17:51:59 -0700 (PDT) | From | David Rientjes <> | Subject | Re: [patch] mm, debug: allow suppressing panic on CONFIG_DEBUG_VM checks |
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On Mon, 22 May 2023, Linus Torvalds wrote:
> On Mon, May 22, 2023 at 11:39 AM David Rientjes <rientjes@google.com> wrote: > > > > I think VM_BUG_ON*() and friends are used to crash the kernel for > > debugging so that we get a crash dump and because some variants don't > > exist for VM_WARN_ON(). > > I do think that from a VM developer standpoint, I think it should be > fine to just effectively turn VM_BUG_ON() into WARN_ON_ONCE() together > with panic_on_warn. > > Maybe we could even extend 'panic_on_warn' to be a bitmap and > effectively have a "don't panic on non-VM warnings" option. >
I hadn't thought of that approach, it would definitely help us achieve our goal of emitting warnings on a small set of production hosts that we don't want to crash. It's also very clean.
Right now kernel.panic_on_warn can either be 0 or 1. We can keep the lowest bit to be "panic on all warnings" and then bit-1 as "panic on debug VM warnings." When CONFIG_DEBUG_VM is enabled, set the new bit by default so there's no behavior change.
Then, we can keep VM_BUG_ON*() and friends around and extend them to check whether they should BUG() after the WARN_ON(1) or not.
On our production hosts, we'll just set kernel.panic_on_oom to 0.
I'll give it a few days to see if anybody else has any comments or concerns; if not, I'll send a v2 based on this. | |