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Make linux(4) set the openfiles soft resource limit to 1024 for Linux

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applications, which often depend on this being the case.  There's a new
sysctl, compat.linux.default_openfiles, to control this behaviour.

Reviewed by:	kevans, emaste, bcr (manpages)
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D25177
This commit is contained in:
Edward Tomasz Napierala 2020-06-10 18:50:46 +00:00
parent c31a6a6612
commit 8c5059e9ea
4 changed files with 41 additions and 1 deletions
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6
share/man/man4/linux.4
View File

@ -24,7 +24,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd December 16, 2019
.Dd June 10, 2020
.Dt LINUX 4
.Os
.Sh NAME
@ -95,6 +95,10 @@ variables and
.Xr loader 8
tunables:
.Bl -tag -width indent
.It Va compat.linux.default_openfiles
Default soft openfiles resource limit for Linux applications.
Set to -1 to disable the limit.
Defaults to 1024.
.It Va compat.linux.emul_path
Path to the Linux run-time environment.
Defaults to

30
sys/compat/linux/linux_emul.c
View File

@ -42,10 +42,12 @@ __FBSDID("$FreeBSD$");
#include <sys/mutex.h>
#include <sys/sx.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/syscallsubr.h>
#include <sys/sysent.h>
#include <compat/linux/linux_emul.h>
#include <compat/linux/linux_mib.h>
#include <compat/linux/linux_misc.h>
#include <compat/linux/linux_persona.h>
#include <compat/linux/linux_util.h>
@ -87,6 +89,32 @@ pem_find(struct proc *p)
return (pem);
}
/*
* Linux apps generally expect the soft open file limit to be set
* to 1024, often iterating over all the file descriptors up to that
* limit instead of using closefrom(2). Give them what they want,
* unless there already is a resource limit in place.
*/
static void
linux_set_default_openfiles(struct thread *td, struct proc *p)
{
struct rlimit rlim;
int error;
if (linux_default_openfiles < 0)
return;
PROC_LOCK(p);
lim_rlimit_proc(p, RLIMIT_NOFILE, &rlim);
PROC_UNLOCK(p);
if (rlim.rlim_cur != rlim.rlim_max ||
rlim.rlim_cur <= linux_default_openfiles)
return;
rlim.rlim_cur = linux_default_openfiles;
error = kern_proc_setrlimit(td, p, RLIMIT_NOFILE, &rlim);
KASSERT(error == 0, ("kern_proc_setrlimit failed"));
}
void
linux_proc_init(struct thread *td, struct thread *newtd, int flags)
{
@ -115,6 +143,8 @@ linux_proc_init(struct thread *td, struct thread *newtd, int flags)
p->p_emuldata = pem;
}
newtd->td_emuldata = em;
linux_set_default_openfiles(td, p);
} else {
p = td->td_proc;

5
sys/compat/linux/linux_mib.c
View File

@ -63,6 +63,11 @@ static unsigned linux_osd_jail_slot;
SYSCTL_NODE(_compat, OID_AUTO, linux, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
"Linux mode");
int linux_default_openfiles = 1024;
SYSCTL_INT(_compat_linux, OID_AUTO, default_openfiles, CTLFLAG_RWTUN,
&linux_default_openfiles, 0,
"Default soft openfiles resource limit, or -1 for unlimited");
int linux_ignore_ip_recverr = 1;
SYSCTL_INT(_compat_linux, OID_AUTO, ignore_ip_recverr, CTLFLAG_RWTUN,
&linux_ignore_ip_recverr, 0, "Ignore enabling IP_RECVERR");

1
sys/compat/linux/linux_mib.h
View File

@ -62,6 +62,7 @@ int linux_kernver(struct thread *td);
#define linux_use26(t) (linux_kernver(t) >= LINUX_KERNVER_2006000)
extern int linux_default_openfiles;
extern int linux_ignore_ip_recverr;
extern int linux_preserve_vstatus;
extern bool linux_map_sched_prio;