Re: git: 7672cbef2c1e - main - pipes: reserve configured percentage of buffers zone to superuser

In message <0A45CDBA-14DF-423E-9A1F-74119AD5C808@freebsd.org>, 
tuexen@freebsd.o
rg writes:
> After building a kernel including these changes, I see a lot of
> negative pipecnt for uid =3D 0
> Installing world also fails due to pipe problems.
> Is this related to one of these changes? Any configuration change =
> needed?
>
> Best regards
> Michael
>

I'm seeing the following from my postfix server. It was rejecting email 
until I reverted this commit.

Sep 20 11:00:44 cwfw postfix/proxymap[18650]: fatal: watchdog_create: pipe: 
Cannot allocate memory
Sep 20 11:00:59 cwfw postfix/pickup[18651]: fatal: watchdog_create: pipe: 
Cannot allocate memory
Sep 20 11:01:21 cwfw postfix/trivial-rewrite[18653]: fatal: 
watchdog_create: pipe: Cannot allocate memory
Sep 20 11:01:45 cwfw postfix/proxymap[18654]: fatal: watchdog_create: pipe: 
Cannot allocate memory
Sep 20 11:01:45 cwfw postfix/qmgr[18655]: fatal: watchdog_create: pipe: 
Cannot allocate memory
Sep 20 11:01:58 cwfw kernel: negative pipecnt for uid = 1006
Sep 20 11:01:58 cwfw syslogd: last message repeated 1 times


-- 
Cheers,
Cy Schubert <Cy.Schubert@cschubert.com>
FreeBSD UNIX:  <cy@FreeBSD.org>   Web:  https://FreeBSD.org
NTP:           <cy@nwtime.org>    Web:  https://nwtime.org

			e^(i*pi)+1=0



> > On 20. Sep 2024, at 08:46, Konstantin Belousov <kib@FreeBSD.org> =
> wrote:
> >=20
> > The branch main has been updated by kib:
> >=20
> > URL: =
> https://cgit.FreeBSD.org/src/commit/?id=3D7672cbef2c1e1267e42bb3aad6a6da93=
> 80f4347f
> >=20
> > commit 7672cbef2c1e1267e42bb3aad6a6da9380f4347f
> > Author:     Konstantin Belousov <kib@FreeBSD.org>
> > AuthorDate: 2024-09-15 06:57:34 +0000
> > Commit:     Konstantin Belousov <kib@FreeBSD.org>
> > CommitDate: 2024-09-20 06:46:07 +0000
> >=20
> >    pipes: reserve configured percentage of buffers zone to superuser
> >=20
> >    Sponsored by:   The FreeBSD Foundation
> >    MFC after:      1 week
> >    Differential revision:  https://reviews.freebsd.org/D46619
> > ---
> > sys/kern/sys_pipe.c | 23 +++++++++++++++++++++--
> > 1 file changed, 21 insertions(+), 2 deletions(-)
> >=20
> > diff --git a/sys/kern/sys_pipe.c b/sys/kern/sys_pipe.c
> > index 7ee2b5c76da3..68b57708d653 100644
> > --- a/sys/kern/sys_pipe.c
> > +++ b/sys/kern/sys_pipe.c
> > @@ -103,6 +103,7 @@
> > #include <sys/stat.h>
> > #include <sys/malloc.h>
> > #include <sys/poll.h>
> > +#include <sys/priv.h>
> > #include <sys/selinfo.h>
> > #include <sys/signalvar.h>
> > #include <sys/syscallsubr.h>
> > @@ -206,6 +207,7 @@ static int pipeallocfail;
> > static int piperesizefail;
> > static int piperesizeallowed =3D 1;
> > static long pipe_mindirect =3D PIPE_MINDIRECT;
> > +static int pipebuf_reserv =3D 2;
> >=20
> > SYSCTL_LONG(_kern_ipc, OID_AUTO, maxpipekva, CTLFLAG_RDTUN | =
> CTLFLAG_NOFETCH,
> >   &maxpipekva, 0, "Pipe KVA limit");
> > @@ -219,6 +221,9 @@ SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizefail, =
> CTLFLAG_RD,
> >  &piperesizefail, 0, "Pipe resize failures");
> > SYSCTL_INT(_kern_ipc, OID_AUTO, piperesizeallowed, CTLFLAG_RW,
> >  &piperesizeallowed, 0, "Pipe resizing allowed");
> > +SYSCTL_INT(_kern_ipc, OID_AUTO, pipebuf_reserv, CTLFLAG_RW,
> > +    &pipebuf_reserv, 0,
> > +    "Superuser-reserved percentage of the pipe buffers space");
> >=20
> > static void pipeinit(void *dummy __unused);
> > static void pipeclose(struct pipe *cpipe);
> > @@ -586,8 +591,22 @@ retry:
> > return (ENOMEM);
> > }
> >=20
> > - error =3D vm_map_find(pipe_map, NULL, 0, (vm_offset_t *)&buffer, =
> size, 0,
> > -    VMFS_ANY_SPACE, VM_PROT_RW, VM_PROT_RW, 0);
> > + vm_map_lock(pipe_map);
> > + if (priv_check(curthread, PRIV_PIPEBUF) !=3D 0 &&
> > +    (vm_map_max(pipe_map) - vm_map_min(pipe_map)) *
> > +    (100 - pipebuf_reserv) / 100 < pipe_map->size + size) {
> > + vm_map_unlock(pipe_map);
> > + if (cpipe->pipe_buffer.buffer =3D=3D NULL &&
> > +    size > SMALL_PIPE_SIZE) {
> > + size =3D SMALL_PIPE_SIZE;
> > + pipefragretry++;
> > + goto retry;
> > + }
> > + return (ENOMEM);
> > + }
> > + error =3D vm_map_find_locked(pipe_map, NULL, 0, (vm_offset_t =
> *)&buffer,
> > +    size, 0, VMFS_ANY_SPACE, VM_PROT_RW, VM_PROT_RW, 0);
> > + vm_map_unlock(pipe_map);
> > if (error !=3D KERN_SUCCESS) {
> > chgpipecnt(cpipe->pipe_pair->pp_owner->cr_ruidinfo, -size, 0);
> > if (cpipe->pipe_buffer.buffer =3D=3D NULL &&
>