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linuxkpi: guarantee allocations of task and mm for interrupt threads

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Create and use zones for task and mm.  Reserve items in zones based on the
estimation of the max number of interrupts in the system.  Use M_USE_RESERVE
to allow to take reserved items when allocation occurs from the interrupt
thread context.

Of course, this would only work first time we allocate the task for
interrupt thread. If interrupt is deallocated and allocated anew,
creating a new thread, it might be that zone is depleted. It still
should be good enough for practical uses.

Reviewed by:	hselasky
Sponsored by:	Mellanox Technologies/NVidia Networking
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2021-03-11 08:34:42 +02:00 committed by Konstantin Belousov
parent 4ce1f6162e
commit 165ba13fb8
1 changed files with 59 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

68
sys/compat/linuxkpi/common/src/linux_current.c
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@ -31,14 +31,22 @@ __FBSDID("$FreeBSD$");
#include <linux/completion.h>
#include <linux/mm.h>
#include <linux/kthread.h>
#include <linux/moduleparam.h>
#include <sys/kernel.h>
#include <sys/eventhandler.h>
#include <sys/malloc.h>
#include <sys/sysctl.h>
#include <vm/uma.h>
#if defined(__i386__) || defined(__amd64__)
extern u_int first_msi_irq, num_msi_irqs;
#endif
static eventhandler_tag linuxkpi_thread_dtor_tag;
static MALLOC_DEFINE(M_LINUX_CURRENT, "linuxcurrent", "LinuxKPI task structure");
static uma_zone_t linux_current_zone;
static uma_zone_t linux_mm_zone;
int
linux_alloc_current(struct thread *td, int flags)
@ -52,13 +60,23 @@ linux_alloc_current(struct thread *td, int flags)
MPASS(td->td_lkpi_task == NULL);
ts = malloc(sizeof(*ts), M_LINUX_CURRENT, flags | M_ZERO);
if (ts == NULL)
return (ENOMEM);
if ((td->td_pflags & TDP_ITHREAD) != 0 || !THREAD_CAN_SLEEP()) {
flags &= ~M_WAITOK;
flags |= M_NOWAIT | M_USE_RESERVE;
}
mm = malloc(sizeof(*mm), M_LINUX_CURRENT, flags | M_ZERO);
ts = uma_zalloc(linux_current_zone, flags | M_ZERO);
if (ts == NULL) {
if ((flags & (M_WAITOK | M_NOWAIT)) == M_WAITOK)
panic("linux_alloc_current: failed to allocate task");
return (ENOMEM);
}
mm = uma_zalloc(linux_mm_zone, flags | M_ZERO);
if (mm == NULL) {
free(ts, M_LINUX_CURRENT);
if ((flags & (M_WAITOK | M_NOWAIT)) == M_WAITOK)
panic("linux_alloc_current: failed to allocate mm");
uma_zfree(linux_current_zone, mm);
return (ENOMEM);
}
@ -111,7 +129,7 @@ linux_alloc_current(struct thread *td, int flags)
PROC_UNLOCK(proc);
/* free mm_struct pointer, if any */
free(mm, M_LINUX_CURRENT);
uma_zfree(linux_mm_zone, mm);
return (0);
}
@ -132,14 +150,14 @@ linux_get_task_mm(struct task_struct *task)
void
linux_mm_dtor(struct mm_struct *mm)
{
free(mm, M_LINUX_CURRENT);
uma_zfree(linux_mm_zone, mm);
}
void
linux_free_current(struct task_struct *ts)
{
mmput(ts->mm);
free(ts, M_LINUX_CURRENT);
uma_zfree(linux_current_zone, ts);
}
static void
@ -229,12 +247,42 @@ linux_task_exiting(struct task_struct *task)
return (ret);
}
static int lkpi_task_resrv;
SYSCTL_INT(_compat_linuxkpi, OID_AUTO, task_struct_reserve,
CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &lkpi_task_resrv, 0,
"Number of struct task and struct mm to reserve for non-sleepable "
"allocations");
static void
linux_current_init(void *arg __unused)
{
lkpi_alloc_current = linux_alloc_current;
linuxkpi_thread_dtor_tag = EVENTHANDLER_REGISTER(thread_dtor,
linuxkpi_thread_dtor, NULL, EVENTHANDLER_PRI_ANY);
TUNABLE_INT_FETCH("compat.linuxkpi.task_struct_reserve",
&lkpi_task_resrv);
if (lkpi_task_resrv == 0) {
#if defined(__i386__) || defined(__amd64__)
/*
* Number of interrupt threads plus per-cpu callout
* SWI threads.
*/
lkpi_task_resrv = first_msi_irq + num_msi_irqs + MAXCPU;
#else
lkpi_task_resrv = 1024; /* XXXKIB arbitrary */
#endif
}
linux_current_zone = uma_zcreate("lkpicurr",
sizeof(struct task_struct), NULL, NULL, NULL, NULL,
UMA_ALIGN_PTR, 0);
uma_zone_reserve(linux_current_zone, lkpi_task_resrv);
uma_prealloc(linux_current_zone, lkpi_task_resrv);
linux_mm_zone = uma_zcreate("lkpimm",
sizeof(struct task_struct), NULL, NULL, NULL, NULL,
UMA_ALIGN_PTR, 0);
uma_zone_reserve(linux_mm_zone, lkpi_task_resrv);
uma_prealloc(linux_mm_zone, lkpi_task_resrv);
}
SYSINIT(linux_current, SI_SUB_EVENTHANDLER, SI_ORDER_SECOND,
linux_current_init, NULL);
@ -260,6 +308,8 @@ linux_current_uninit(void *arg __unused)
sx_sunlock(&allproc_lock);
EVENTHANDLER_DEREGISTER(thread_dtor, linuxkpi_thread_dtor_tag);
lkpi_alloc_current = linux_alloc_current_noop;
uma_zdestroy(linux_current_zone);
uma_zdestroy(linux_mm_zone);
}
SYSUNINIT(linux_current, SI_SUB_EVENTHANDLER, SI_ORDER_SECOND,
linux_current_uninit, NULL);