Unverified Commit 54e6842d authored by Mike Christie's avatar Mike Christie Committed by Christian Brauner (Microsoft)
Browse files

fork/vm: Move common PF_IO_WORKER behavior to new flag 



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: default avatarMike Christie <michael.christie@oracle.com>
Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarChristian Brauner (Microsoft) <brauner@kernel.org>
parent c81cc581

include/linux/sched.h

+1 −1
Original line number Diff line number Diff line
@@ -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 */

include/linux/sched/task.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

kernel/fork.c

+3 −0
Original line number Diff line number Diff line
@@ -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);

mm/vmscan.c

+2 −2
Original line number Diff line number Diff line
@@ -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;

	}