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authorMauricio Faria de Oliveira <mfo@igalia.com>2025-10-01 14:56:11 -0300
committerAndrew Morton <akpm@linux-foundation.org>2025-11-16 17:27:59 -0800
commit0de9a442eeba4a6435af74120822b10b12ab8449 (patch)
tree882a71a054bdcd31c1fa78c4b18ee782cf27f6a4 /Documentation/mm
parent5513cfbcf4da97ba0476d63e7670fdfcde59580f (diff)
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: 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>
Diffstat (limited to 'Documentation/mm')
-rw-r--r--Documentation/mm/page_owner.rst32
1 files changed, 31 insertions, 1 deletions
diff --git a/Documentation/mm/page_owner.rst b/Documentation/mm/page_owner.rst
index 3a45a20fc05a..6b12f3b007ec 100644
--- a/Documentation/mm/page_owner.rst
+++ b/Documentation/mm/page_owner.rst
@@ -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