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mm,page_owner: update Documentation regarding page_owner_stacks

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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: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Marco Elver <elver@google.com>
Acked-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Oscar Salvador 2024-02-15 22:59:07 +01:00 committed by Andrew Morton
parent 05bb6f4e82
commit ba6fe53772
1 changed files with 45 additions and 0 deletions
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45
Documentation/mm/page_owner.rst
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@ -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