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fork/vm: Move common PF_IO_WORKER behavior to new flag

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This adds a new flag, PF_USER_WORKER, that's used for behavior common to
to both PF_IO_WORKER and users like vhost which will use a new helper
instead of create_io_thread because they require different behavior for
operations like signal handling.

The common behavior PF_USER_WORKER covers is the vm reclaim handling.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
This commit is contained in:
Mike Christie 2023-03-10 16:03:26 -06:00 committed by Christian Brauner (Microsoft)
parent c81cc5819f
commit 54e6842d07
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GPG Key ID: 91C61BC06578DCA2
4 changed files with 7 additions and 3 deletions
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2
include/linux/sched.h
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@ -1729,7 +1729,7 @@ extern struct pid *cad_pid;
#define PF_MEMALLOC 0x00000800 /* Allocating memory */
#define PF_NPROC_EXCEEDED 0x00001000 /* set_user() noticed that RLIMIT_NPROC was exceeded */
#define PF_USED_MATH 0x00002000 /* If unset the fpu must be initialized before use */
#define PF__HOLE__00004000 0x00004000
#define PF_USER_WORKER 0x00004000 /* Kernel thread cloned from userspace thread */
#define PF_NOFREEZE 0x00008000 /* This thread should not be frozen */
#define PF__HOLE__00010000 0x00010000
#define PF_KSWAPD 0x00020000 /* I am kswapd */

1
include/linux/sched/task.h
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@ -27,6 +27,7 @@ struct kernel_clone_args {
int exit_signal;
u32 kthread:1;
u32 io_thread:1;
u32 user_worker:1;
unsigned long stack;
unsigned long stack_size;
unsigned long tls;

3
kernel/fork.c
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@ -2103,6 +2103,8 @@ static __latent_entropy struct task_struct *copy_process(
p->flags &= ~PF_KTHREAD;
if (args->kthread)
p->flags |= PF_KTHREAD;
if (args->user_worker)
p->flags |= PF_USER_WORKER;
if (args->io_thread) {
/*
* Mark us an IO worker, and block any signal that isn't
@ -2630,6 +2632,7 @@ struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
.fn = fn,
.fn_arg = arg,
.io_thread = 1,
.user_worker = 1,
};
return copy_process(NULL, 0, node, &args);

4
mm/vmscan.c
View File

@ -1151,12 +1151,12 @@ void reclaim_throttle(pg_data_t *pgdat, enum vmscan_throttle_state reason)
DEFINE_WAIT(wait);
/*
* Do not throttle IO workers, kthreads other than kswapd or
* Do not throttle user workers, kthreads other than kswapd or
* workqueues. They may be required for reclaim to make
* forward progress (e.g. journalling workqueues or kthreads).
*/
if (!current_is_kswapd() &&
current->flags & (PF_IO_WORKER|PF_KTHREAD)) {
current->flags & (PF_USER_WORKER|PF_KTHREAD)) {
cond_resched();
return;
}