Commit 0de9a442 authored by Mauricio Faria de Oliveira's avatar Mauricio Faria de Oliveira Committed by Andrew Morton
Browse files

mm/page_owner: update Documentation with 'show_handles' and 'show_stacks_handles' 

Describe and provide examples for 'show_handles' and 'show_stacks_handles'.

Link: https://lkml.kernel.org/r/20251001175611.575861-6-mfo@igalia.com


Signed-off-by: default avatarMauricio Faria de Oliveira <mfo@igalia.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 5513cfbc

Documentation/mm/page_owner.rst

+31 −1
Original line number Diff line number Diff line
@@ -27,7 +27,10 @@ enabled. Other usages are more than welcome. 
It can also be used to show all the stacks and their current number of

allocated base pages, 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.

allocation and free operation. It's also possible to show only a numeric

identifier of all the stacks (without stack traces) and their number of

allocated base pages (faster to read and parse, eg, for monitoring) that

can be matched with stacks later (show_handles and show_stacks_handles).



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
@@ -116,6 +119,33 @@ Usage 
	nr_base_pages: 20824

	...



	cat /sys/kernel/debug/page_owner_stacks/show_handles > handles_7000.txt

	cat handles_7000.txt

	handle: 42

	nr_base_pages: 20824

	...



	cat /sys/kernel/debug/page_owner_stacks/show_stacks_handles > stacks_handles.txt

	cat stacks_handles.txt

	 post_alloc_hook+0x177/0x1a0

	 get_page_from_freelist+0xd01/0xd80

	 __alloc_pages+0x39e/0x7e0

	 alloc_pages_mpol+0x22e/0x490

	 folio_alloc+0xd5/0x110

	 filemap_alloc_folio+0x78/0x230

	 page_cache_ra_order+0x287/0x6f0

	 filemap_get_pages+0x517/0x1160

	 filemap_read+0x304/0x9f0

	 xfs_file_buffered_read+0xe6/0x1d0 [xfs]

	 xfs_file_read_iter+0x1f0/0x380 [xfs]

	 __kernel_read+0x3b9/0x730

	 kernel_read_file+0x309/0x4d0

	 __do_sys_finit_module+0x381/0x730

	 do_syscall_64+0x8d/0x150

	 entry_SYSCALL_64_after_hwframe+0x62/0x6a

	handle: 42

	...



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

	./page_owner_sort page_owner_full.txt sorted_page_owner.txt