Commit 739100c8 authored by Stefan Roesch's avatar Stefan Roesch Committed by Andrew Morton
Browse files

mm: add tracepoints to ksm 

This adds the following tracepoints to ksm:
- start / stop scan
- ksm enter / exit
- merge a page
- merge a page with ksm
- remove a page
- remove a rmap item

This patch has been split off from the RFC patch series "mm:
process/cgroup ksm support".

Link: https://lkml.kernel.org/r/20230210214645.2720847-1-shr@devkernel.io


Signed-off-by: default avatarStefan Roesch <shr@devkernel.io>
Reviewed-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 77f68ebe

MAINTAINERS

+1 −0
Original line number Diff line number Diff line
@@ -13409,6 +13409,7 @@ F: include/linux/memory_hotplug.h 
F:	include/linux/mm.h

F:	include/linux/mmzone.h

F:	include/linux/pagewalk.h

F:	include/trace/events/ksm.h

F:	mm/

F:	tools/mm/

F:	tools/testing/selftests/mm/

include/trace/events/ksm.h

0 → 100644
+251 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#undef TRACE_SYSTEM

#define TRACE_SYSTEM ksm



#if !defined(_TRACE_KSM_H) || defined(TRACE_HEADER_MULTI_READ)

#define _TRACE_KSM_H



#include <linux/tracepoint.h>



/**

 * ksm_scan_template - called for start / stop scan

 *

 * @seq:		sequence number of scan

 * @rmap_entries:	actual number of rmap entries

 *

 * Allows to trace the start / stop of a ksm scan.

 */

DECLARE_EVENT_CLASS(ksm_scan_template,



	TP_PROTO(int seq, u32 rmap_entries),



	TP_ARGS(seq, rmap_entries),



	TP_STRUCT__entry(

		__field(int,	seq)

		__field(u32,	rmap_entries)

	),



	TP_fast_assign(

		__entry->seq		= seq;

		__entry->rmap_entries	= rmap_entries;

	),



	TP_printk("seq %d rmap size %d",

			__entry->seq, __entry->rmap_entries)

);



/**

 * ksm_start_scan - called after a new ksm scan is started

 *

 * @seq:		sequence number of scan

 * @rmap_entries:	actual number of rmap entries

 *

 * Allows to trace the start of a ksm scan.

 */

DEFINE_EVENT(ksm_scan_template, ksm_start_scan,



	TP_PROTO(int seq, u32 rmap_entries),



	TP_ARGS(seq, rmap_entries)

);



/**

 * ksm_stop_scan - called after a new ksm scan has completed

 *

 * @seq:		sequence number of scan

 * @rmap_entries:	actual number of rmap entries

 *

 * Allows to trace the completion of a ksm scan.

 */

DEFINE_EVENT(ksm_scan_template, ksm_stop_scan,



	TP_PROTO(int seq, u32 rmap_entries),



	TP_ARGS(seq, rmap_entries)

);



/**

 * ksm_enter - called after a new process has been added / removed from ksm

 *

 * @mm:			address of the mm object of the process

 *

 * Allows to trace the when a process has been added or removed from ksm.

 */

DECLARE_EVENT_CLASS(ksm_enter_exit_template,



	TP_PROTO(void *mm),



	TP_ARGS(mm),



	TP_STRUCT__entry(

		__field(void *,		mm)

	),



	TP_fast_assign(

		__entry->mm	= mm;

	),



	TP_printk("mm %p", __entry->mm)

);



/**

 * ksm_enter - called after a new process has been added to ksm

 *

 * @mm:			address of the mm object of the process

 *

 * Allows to trace the when a process has been added to ksm.

 */

DEFINE_EVENT(ksm_enter_exit_template, ksm_enter,



	TP_PROTO(void *mm),



	TP_ARGS(mm)

);



/**

 * ksm_exit - called after a new process has been removed from ksm

 *

 * @mm:			address of the mm object of the process

 *

 * Allows to trace the when a process has been removed from ksm.

 */

DEFINE_EVENT(ksm_enter_exit_template, ksm_exit,



	TP_PROTO(void *mm),



	TP_ARGS(mm)

);



/**

 * ksm_merge_one_page - called after a page has been merged

 *

 * @pfn:		page frame number of ksm page

 * @rmap_item:		address of rmap_item  object

 * @mm:			address of the process mm struct

 * @err:		success

 *

 * Allows to trace the ksm merging of individual pages.

 */

TRACE_EVENT(ksm_merge_one_page,



	TP_PROTO(unsigned long pfn, void *rmap_item, void *mm, int err),



	TP_ARGS(pfn, rmap_item, mm, err),



	TP_STRUCT__entry(

		__field(unsigned long,	pfn)

		__field(void *,		rmap_item)

		__field(void *,		mm)

		__field(int,		err)

	),



	TP_fast_assign(

		__entry->pfn		= pfn;

		__entry->rmap_item	= rmap_item;

		__entry->mm		= mm;

		__entry->err		= err;

	),



	TP_printk("ksm pfn %lu rmap_item %p mm %p error %d",

			__entry->pfn, __entry->rmap_item, __entry->mm, __entry->err)

);



/**

 * ksm_merge_with_ksm_page - called after a page has been merged with a ksm page

 *

 * @ksm_page:		address ksm page

 * @pfn:		page frame number of ksm page

 * @rmap_item:		address of rmap_item  object

 * @mm:			address of the mm object of the process

 * @err:		success

 *

 * Allows to trace the merging of a page with a ksm page.

 */

TRACE_EVENT(ksm_merge_with_ksm_page,



	TP_PROTO(void *ksm_page, unsigned long pfn, void *rmap_item, void *mm, int err),



	TP_ARGS(ksm_page, pfn, rmap_item, mm, err),



	TP_STRUCT__entry(

		__field(void *,		ksm_page)

		__field(unsigned long,	pfn)

		__field(void *,		rmap_item)

		__field(void *,		mm)

		__field(int,		err)

	),



	TP_fast_assign(

		__entry->ksm_page	= ksm_page;

		__entry->pfn		= pfn;

		__entry->rmap_item	= rmap_item;

		__entry->mm		= mm;

		__entry->err		= err;

	),



	TP_printk("%spfn %lu rmap_item %p mm %p error %d",

		  (__entry->ksm_page ? "ksm " : ""),

		  __entry->pfn, __entry->rmap_item, __entry->mm, __entry->err)

);



/**

 * ksm_remove_ksm_page - called after a ksm page has been removed

 *

 * @pfn:		page frame number of ksm page

 *

 * Allows to trace the removing of stable ksm pages.

 */

TRACE_EVENT(ksm_remove_ksm_page,



	TP_PROTO(unsigned long pfn),



	TP_ARGS(pfn),



	TP_STRUCT__entry(

		__field(unsigned long, pfn)

	),



	TP_fast_assign(

		__entry->pfn = pfn;

	),



	TP_printk("pfn %lu", __entry->pfn)

);



/**

 * ksm_remove_rmap_item - called after a rmap_item has been removed from the

 *                        stable tree

 *

 * @pfn:		page frame number of ksm page

 * @rmap_item:		address of rmap_item  object

 * @mm:			address of the process mm struct

 *

 * Allows to trace the removal of pages from the stable tree list.

 */

TRACE_EVENT(ksm_remove_rmap_item,



	TP_PROTO(unsigned long pfn, void *rmap_item, void *mm),



	TP_ARGS(pfn, rmap_item, mm),



	TP_STRUCT__entry(

		__field(unsigned long,	pfn)

		__field(void *,		rmap_item)

		__field(void *,		mm)

	),



	TP_fast_assign(

		__entry->pfn		= pfn;

		__entry->rmap_item	= rmap_item;

		__entry->mm		= mm;

	),



	TP_printk("pfn %lu rmap_item %p mm %p",

			__entry->pfn, __entry->rmap_item, __entry->mm)

);



#endif /* _TRACE_KSM_H */



/* This part must be outside protection */

#include <trace/define_trace.h>

mm/ksm.c

+19 −2
Original line number Diff line number Diff line
@@ -45,6 +45,9 @@ 
#include "internal.h"

#include "mm_slot.h"



#define CREATE_TRACE_POINTS

#include <trace/events/ksm.h>



#ifdef CONFIG_NUMA

#define NUMA(x)		(x)

#define DO_NUMA(x)	do { (x); } while (0)
@@ -633,10 +636,12 @@ static void remove_node_from_stable_tree(struct ksm_stable_node *stable_node) 
	BUG_ON(stable_node->rmap_hlist_len < 0);



	hlist_for_each_entry(rmap_item, &stable_node->hlist, hlist) {

		if (rmap_item->hlist.next)

		if (rmap_item->hlist.next) {

			ksm_pages_sharing--;

		else

			trace_ksm_remove_rmap_item(stable_node->kpfn, rmap_item, rmap_item->mm);

		} else {

			ksm_pages_shared--;

		}



		rmap_item->mm->ksm_merging_pages--;
@@ -657,6 +662,7 @@ static void remove_node_from_stable_tree(struct ksm_stable_node *stable_node) 
	BUILD_BUG_ON(STABLE_NODE_DUP_HEAD <= &migrate_nodes);

	BUILD_BUG_ON(STABLE_NODE_DUP_HEAD >= &migrate_nodes + 1);



	trace_ksm_remove_ksm_page(stable_node->kpfn);

	if (stable_node->head == &migrate_nodes)

		list_del(&stable_node->list);

	else
@@ -1324,6 +1330,8 @@ static int try_to_merge_with_ksm_page(struct ksm_rmap_item *rmap_item, 
	get_anon_vma(vma->anon_vma);

out:

	mmap_read_unlock(mm);

	trace_ksm_merge_with_ksm_page(kpage, page_to_pfn(kpage ? kpage : page),

				rmap_item, mm, err);

	return err;

}
@@ -2142,6 +2150,9 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite 
		if (vma) {

			err = try_to_merge_one_page(vma, page,

					ZERO_PAGE(rmap_item->address));

			trace_ksm_merge_one_page(

				page_to_pfn(ZERO_PAGE(rmap_item->address)),

				rmap_item, mm, err);

		} else {

			/*

			 * If the vma is out of date, we do not need to
@@ -2264,6 +2275,8 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page) 


	mm_slot = ksm_scan.mm_slot;

	if (mm_slot == &ksm_mm_head) {

		trace_ksm_start_scan(ksm_scan.seqnr, ksm_rmap_items);



		/*

		 * A number of pages can hang around indefinitely on per-cpu

		 * pagevecs, raised page count preventing write_protect_page
@@ -2414,6 +2427,7 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page) 
	if (mm_slot != &ksm_mm_head)

		goto next_mm;



	trace_ksm_stop_scan(ksm_scan.seqnr, ksm_rmap_items);

	ksm_scan.seqnr++;

	return NULL;

}
@@ -2565,6 +2579,7 @@ int __ksm_enter(struct mm_struct *mm) 
	if (needs_wakeup)

		wake_up_interruptible(&ksm_thread_wait);



	trace_ksm_enter(mm);

	return 0;

}
@@ -2606,6 +2621,8 @@ void __ksm_exit(struct mm_struct *mm) 
		mmap_write_lock(mm);

		mmap_write_unlock(mm);

	}



	trace_ksm_exit(mm);

}



struct page *ksm_might_need_to_copy(struct page *page,