Commit b698f0a1 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

mm/fs: delete PF_SWAPWRITE 

PF_SWAPWRITE has been redundant since v3.2 commit ee72886d ("mm:
vmscan: do not writeback filesystem pages in direct reclaim").

Coincidentally, NeilBrown's current patch "remove inode_congested()"
deletes may_write_to_inode(), which appeared to be the one function which
took notice of PF_SWAPWRITE.  But if you study the old logic, and the
conditions under which may_write_to_inode() was called, you discover that
flag and function have been pointless for a decade.

Link: https://lkml.kernel.org/r/75e80e7-742d-e3bd-531-614db8961e4@google.com


Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Jan Kara <jack@suse.de>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d794103d

fs/fs-writeback.c

+0 −3
Original line number Diff line number Diff line
@@ -2197,7 +2197,6 @@ void wb_workfn(struct work_struct *work) 
	long pages_written;



	set_worker_desc("flush-%s", bdi_dev_name(wb->bdi));

	current->flags |= PF_SWAPWRITE;



	if (likely(!current_is_workqueue_rescuer() ||

		   !test_bit(WB_registered, &wb->state))) {
@@ -2226,8 +2225,6 @@ void wb_workfn(struct work_struct *work) 
		wb_wakeup(wb);

	else if (wb_has_dirty_io(wb) && dirty_writeback_interval)

		wb_wakeup_delayed(wb);



	current->flags &= ~PF_SWAPWRITE;

}



/*

fs/xfs/libxfs/xfs_btree.c

+1 −1
Original line number Diff line number Diff line
@@ -2818,7 +2818,7 @@ xfs_btree_split_worker( 
	 * in any way.

	 */

	if (args->kswapd)

		new_pflags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;

		new_pflags |= PF_MEMALLOC | PF_KSWAPD;



	current_set_flags_nested(&pflags, new_pflags);

	xfs_trans_set_context(args->cur->bc_tp);

include/linux/sched.h

+0 −1
Original line number Diff line number Diff line
@@ -1689,7 +1689,6 @@ extern struct pid *cad_pid; 
						 * I am cleaning dirty pages from some other bdi. */

#define PF_KTHREAD		0x00200000	/* I am a kernel thread */

#define PF_RANDOMIZE		0x00400000	/* Randomize virtual address space */

#define PF_SWAPWRITE		0x00800000	/* Allowed to write to swap */

#define PF_NO_SETAFFINITY	0x04000000	/* Userland is not allowed to meddle with cpus_mask */

#define PF_MCE_EARLY		0x08000000      /* Early kill for mce process policy */

#define PF_MEMALLOC_PIN		0x10000000	/* Allocation context constrained to zones which allow long term pinning. */

mm/migrate.c

+0 −7
Original line number Diff line number Diff line
@@ -1350,7 +1350,6 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, 
	bool is_thp = false;

	struct page *page;

	struct page *page2;

	int swapwrite = current->flags & PF_SWAPWRITE;

	int rc, nr_subpages;

	LIST_HEAD(ret_pages);

	LIST_HEAD(thp_split_pages);
@@ -1359,9 +1358,6 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, 


	trace_mm_migrate_pages_start(mode, reason);



	if (!swapwrite)

		current->flags |= PF_SWAPWRITE;



thp_subpage_migration:

	for (pass = 0; pass < 10 && (retry || thp_retry); pass++) {

		retry = 0;
@@ -1516,9 +1512,6 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page, 
	trace_mm_migrate_pages(nr_succeeded, nr_failed_pages, nr_thp_succeeded,

			       nr_thp_failed, nr_thp_split, mode, reason);



	if (!swapwrite)

		current->flags &= ~PF_SWAPWRITE;



	if (ret_succeeded)

		*ret_succeeded = nr_succeeded;

mm/vmscan.c

+2 −6
Original line number Diff line number Diff line
@@ -4457,7 +4457,7 @@ static int kswapd(void *p) 
	 * us from recursively trying to free more memory as we're

	 * trying to free the first piece of memory in the first place).

	 */

	tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;

	tsk->flags |= PF_MEMALLOC | PF_KSWAPD;

	set_freezable();



	WRITE_ONCE(pgdat->kswapd_order, 0);
@@ -4508,7 +4508,7 @@ static int kswapd(void *p) 
			goto kswapd_try_sleep;

	}



	tsk->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD);

	tsk->flags &= ~(PF_MEMALLOC | PF_KSWAPD);



	return 0;

}
@@ -4749,11 +4749,8 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in 
	fs_reclaim_acquire(sc.gfp_mask);

	/*

	 * We need to be able to allocate from the reserves for RECLAIM_UNMAP

	 * and we also need to be able to write out pages for RECLAIM_WRITE

	 * and RECLAIM_UNMAP.

	 */

	noreclaim_flag = memalloc_noreclaim_save();

	p->flags |= PF_SWAPWRITE;

	set_task_reclaim_state(p, &sc.reclaim_state);



	if (node_pagecache_reclaimable(pgdat) > pgdat->min_unmapped_pages) {
@@ -4767,7 +4764,6 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in 
	}



	set_task_reclaim_state(p, NULL);

	current->flags &= ~PF_SWAPWRITE;

	memalloc_noreclaim_restore(noreclaim_flag);

	fs_reclaim_release(sc.gfp_mask);

	psi_memstall_leave(&pflags);