Date: Mon, 28 Feb 2022 11:04:28 -0800 From: Mark Millard <marklmi@yahoo.com> To: Mark Johnston <markj@FreeBSD.org>, FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org> Cc: freebsd-current <freebsd-current@freebsd.org>, dev-commits-src-main@freebsd.org Subject: Re: git: 4a864f624a70 - main - vm_pageout: Print a more accurate message to the console before an OOM kill [MFC in time for 13.1?] Message-ID: <49BCAD72-1D83-4D85-912F-DF6FD92BB440@yahoo.com> In-Reply-To: <B052F35A-FD2C-4FAB-A3D6-D7D1B3C0AAED@yahoo.com> References: <1EF55D96-F7E3-4AA6-A331-782362A70878.ref@yahoo.com> <1EF55D96-F7E3-4AA6-A331-782362A70878@yahoo.com> <YeLuZnR249sw3iCw@nuc> <B052F35A-FD2C-4FAB-A3D6-D7D1B3C0AAED@yahoo.com>
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On 2022-Feb-26, at 17:10, Mark Millard <marklmi@yahoo.com> wrote:
> On 2022-Jan-15, at 07:55, Mark Johnston <markj@FreeBSD.org> wrote:
>=20
>> On Fri, Jan 14, 2022 at 09:38:56PM -0800, Mark Millard wrote:
>>> Thanks. This will allow me to remove part of my personal additions
>>> in this area --and my having to explain the misnomer when trying
>>> to help someone analyze why they end up with OOM activity so they
>>> can figure out what to do about it.
>>>=20
>>> There seem to be two separate sources of VM_OOM_SWAPZ. Showing
>>> my personal additions for them (just making them explicit in the
>>> sequence of messages generated):
>>>=20
>>> diff --git a/sys/vm/swap_pager.c b/sys/vm/swap_pager.c
>>> index 01cf9233329f..280621ca51be 100644
>>> --- a/sys/vm/swap_pager.c
>>> +++ b/sys/vm/swap_pager.c
>>> @@ -2091,6 +2091,7 @@ swp_pager_meta_build(vm_object_t object, =
vm_pindex_t pindex, daddr_t swapblk)
>>> 0, 1))
>>> printf("swap blk zone =
exhausted, "
>>> "increase =
kern.maxswzone\n");
>>> + printf("swp_pager_meta_build: swap =
blk uma zone exhausted\n");
>>> vm_pageout_oom(VM_OOM_SWAPZ);
>>> pause("swzonxb", 10);
>>> } else
>>> @@ -2121,6 +2122,7 @@ swp_pager_meta_build(vm_object_t object, =
vm_pindex_t pindex, daddr_t swapblk)
>>> 0, 1))
>>> printf("swap pctrie zone =
exhausted, "
>>> "increase =
kern.maxswzone\n");
>>> + printf("swp_pager_meta_build: swap =
pctrie uma zone exhausted\n");
>>> vm_pageout_oom(VM_OOM_SWAPZ);
>>> pause("swzonxp", 10);
>>> } else
>>>=20
>>> Care to comment on the distinctions and why there are two
>>> contexts classified as "out of swap space"? Would either
>>> one show the swap space as (nearly?) all used in, say, top?
>>> Or might one of them still end up looking like a misnomer
>>> from just a top (or whatever) display?
>>=20
>> Hmm, those cases should likely be changed from "out of swap space" to
>> "failed to allocate swap metadata" or something like that.
>=20
> The above does not seem to have happened yet in main [so: 14].
>=20
> Will 13.1 get an MFC of 4a864f624a70 in time, possibly with the
> above change also in place to fully avoid misnomer reporting
> that misleads folks?
>=20
> 4a864f624a70 listed:
>=20
> MFC after: 2 weeks
>=20
> but it has been more than a month.
>=20
>> . . .
>>=20
>=20
Thanks for the stable/13 MFC as 13ba1d283676. It
provides a big improvement over the prior messaging
for the OOM kills.
For reference, I do still view:
+ case VM_OOM_SWAPZ:
+ reason =3D "out of swap space";
+ break;
as using a confusing misnomer ("swap space") for its
message. But, so far as I know, VM_OOM_SWAPZ is a
rarity and possibly very difficult to produce. If
so, any confusions from the message should also be
rare.
=3D=3D=3D
Mark Millard
marklmi at yahoo.com
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