Commit ba6fe537 authored by Oscar Salvador's avatar Oscar Salvador Committed by Andrew Morton
Browse files

mm,page_owner: update Documentation regarding page_owner_stacks 

Update page_owner documentation including the new page_owner_stacks
feature to show how it can be used.

Link: https://lkml.kernel.org/r/20240215215907.20121-8-osalvador@suse.de


Signed-off-by: default avatarOscar Salvador <osalvador@suse.de>
Reviewed-by: default avatarVlastimil Babka <vbabka@suse.cz>
Reviewed-by: default avatarMarco Elver <elver@google.com>
Acked-by: default avatarAndrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 05bb6f4e

Documentation/mm/page_owner.rst

+45 −0
Original line number Diff line number Diff line
@@ -24,6 +24,11 @@ fragmentation statistics can be obtained through gfp flag information of 
each page. It is already implemented and activated if page owner is

enabled. Other usages are more than welcome.



It can also be used to show all the stacks and their outstanding

allocations, which gives us a quick overview of where the memory is going

without the need to screen through all the pages and match the allocation

and free operation.



page owner is disabled by default. So, if you'd like to use it, you need

to add "page_owner=on" to your boot cmdline. If the kernel is built

with page owner and page owner is disabled in runtime due to not enabling
@@ -68,6 +73,46 @@ Usage 


4) Analyze information from page owner::



	cat /sys/kernel/debug/page_owner_stacks/show_stacks > stacks.txt

	cat stacks.txt

	 prep_new_page+0xa9/0x120

	 get_page_from_freelist+0x7e6/0x2140

	 __alloc_pages+0x18a/0x370

	 new_slab+0xc8/0x580

	 ___slab_alloc+0x1f2/0xaf0

	 __slab_alloc.isra.86+0x22/0x40

	 kmem_cache_alloc+0x31b/0x350

	 __khugepaged_enter+0x39/0x100

	 dup_mmap+0x1c7/0x5ce

	 copy_process+0x1afe/0x1c90

	 kernel_clone+0x9a/0x3c0

	 __do_sys_clone+0x66/0x90

	 do_syscall_64+0x7f/0x160

	 entry_SYSCALL_64_after_hwframe+0x6c/0x74

	stack_count: 234

	...

	...

	echo 7000 > /sys/kernel/debug/page_owner_stacks/count_threshold

	cat /sys/kernel/debug/page_owner_stacks/show_stacks> stacks_7000.txt

	cat stacks_7000.txt

	 prep_new_page+0xa9/0x120

	 get_page_from_freelist+0x7e6/0x2140

	 __alloc_pages+0x18a/0x370

	 alloc_pages_mpol+0xdf/0x1e0

	 folio_alloc+0x14/0x50

	 filemap_alloc_folio+0xb0/0x100

	 page_cache_ra_unbounded+0x97/0x180

	 filemap_fault+0x4b4/0x1200

	 __do_fault+0x2d/0x110

	 do_pte_missing+0x4b0/0xa30

	 __handle_mm_fault+0x7fa/0xb70

	 handle_mm_fault+0x125/0x300

	 do_user_addr_fault+0x3c9/0x840

	 exc_page_fault+0x68/0x150

	 asm_exc_page_fault+0x22/0x30

	stack_count: 8248

	...



	cat /sys/kernel/debug/page_owner > page_owner_full.txt

	./page_owner_sort page_owner_full.txt sorted_page_owner.txt