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

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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: Mauricio 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: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Mauricio Faria de Oliveira 2025-10-01 14:56:11 -03:00 • committed by Andrew Morton
parent 5513cfbcf4
commit 0de9a442ee
1 changed files with 31 additions and 1 deletions
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32
Documentation/mm/page_owner.rst
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@ -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