The patch titled Subject: mm,page_owner: update Documentation regarding page_owner_stacks has been added to the -mm mm-unstable branch. Its filename is mmpage_owner-update-documentation-regarding-page_owner_stacks.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mmpage_owner-update-documentation-regarding-page_owner_stacks.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Oscar Salvador <osalvador@xxxxxxx> Subject: mm,page_owner: update Documentation regarding page_owner_stacks Date: Thu, 15 Feb 2024 22:59:07 +0100 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@xxxxxxx Signed-off-by: Oscar Salvador <osalvador@xxxxxxx> Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx> Reviewed-by: Marco Elver <elver@xxxxxxxxxx> Cc: Alexander Potapenko <glider@xxxxxxxxxx> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Documentation/mm/page_owner.rst | 45 ++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) --- a/Documentation/mm/page_owner.rst~mmpage_owner-update-documentation-regarding-page_owner_stacks +++ a/Documentation/mm/page_owner.rst @@ -24,6 +24,11 @@ fragmentation statistics can be obtained 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 _ Patches currently in -mm which might be from osalvador@xxxxxxx are lib-stackdepot-fix-first-entry-having-a-0-handle.patch lib-stackdepot-move-stack_record-struct-definition-into-the-header.patch mmpage_owner-maintain-own-list-of-stack_records-structs.patch mmpage_owner-implement-the-tracking-of-the-stacks-count.patch mmpage_owner-display-all-stacks-and-their-count.patch mmpage_owner-filter-out-stacks-by-a-threshold.patch mmpage_owner-update-documentation-regarding-page_owner_stacks.patch