From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1995613AA59 for ; Thu, 4 Apr 2024 21:13:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712265205; cv=none; b=J1GTI1mlrov+H4ixLEfe2AAgJ6+xIzOZmAGFL2pSNo/bVneDF3dx5GbTmob9Vc0SXiPcvND4EVHo/fN4XuTqIjpF88+SD3oNT4N2geNPevT3JM10D612B7NqZppj5DZe68vpTK4mOF1o8G1lRD0RtZHV//hWvEbwlpMfeJuZq/g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712265205; c=relaxed/simple; bh=684UI4MxI+4PJikHE59pJdEY6qOeUEcESd4ICeGclvY=; h=Date:To:From:Subject:Message-Id; b=T/QtlGVu0LlOnBVeWzGU3Cvg2Ru7BF/6e+yJeGu20v323Aa0X2deSs05fkjs1VMXgV05CJZ47TkIhCpdtUnR0iRaW012NzvN1zs+DRdVrc+o4mP1eu+MslNRn/DoJnqrhH9MCOiDNcp704Sv8MfjDEVIAEwjiYN00gJ3A+bq/10= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=bbIHmgKi; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="bbIHmgKi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 87AE5C43390; Thu, 4 Apr 2024 21:13:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1712265204; bh=684UI4MxI+4PJikHE59pJdEY6qOeUEcESd4ICeGclvY=; h=Date:To:From:Subject:From; b=bbIHmgKibj9pWnG7n+yPCSV6Gbqsf21snHu5owdlywl82THcrk8uZiCbrkA8q79Kj U8PPbFUsX1Qe1Z1ABBIEJC602/11cJf96/Y+D3olIhnKH4DzqWb65AnyAekYbDgBHx 9iPVzjAKVxfLOkvyWjCjpflC/zn6/00UyTBo6f5o= Date: Thu, 04 Apr 2024 14:13:23 -0700 To: mm-commits@vger.kernel.org,vbabka@suse.cz,mhocko@suse.com,glider@google.com,elver@google.com,andreyknvl@gmail.com,alexghiti@rivosinc.com,osalvador@suse.de,akpm@linux-foundation.org From: Andrew Morton Subject: + mmpage_owner-fix-accounting-of-pages-when-migrating.patch added to mm-hotfixes-unstable branch Message-Id: <20240404211324.87AE5C43390@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm,page_owner: fix accounting of pages when migrating has been added to the -mm mm-hotfixes-unstable branch. Its filename is mmpage_owner-fix-accounting-of-pages-when-migrating.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mmpage_owner-fix-accounting-of-pages-when-migrating.patch This patch will later appear in the mm-hotfixes-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 Subject: mm,page_owner: fix accounting of pages when migrating Date: Thu, 4 Apr 2024 09:07:01 +0200 Upon migration, new allocated pages are being given the handle of the old pages. This is problematic because it means that for the stack which allocated the old page, we will be substracting the old page + the new one when that page is freed, creating an accounting imbalance. There is an interest in keeping it that way, as otherwise the output will biased towards migration stacks should those operations occur often, but that is not really helpful. The link from the new page to the old stack is being performed by calling __update_page_owner_handle() in __folio_copy_owner(). The only thing that is left is to link the migrate stack to the old page, so the old page will be subtracted from the migrate stack, avoiding by doing so any possible imbalance. Link: https://lkml.kernel.org/r/20240404070702.2744-4-osalvador@suse.de Fixes: 217b2119b9e2 ("mm,page_owner: implement the tracking of the stacks count") Signed-off-by: Oscar Salvador Reviewed-by: Vlastimil Babka Cc: Alexander Potapenko Cc: Alexandre Ghiti Cc: Andrey Konovalov Cc: Marco Elver Cc: Michal Hocko Signed-off-by: Andrew Morton --- mm/page_owner.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) --- a/mm/page_owner.c~mmpage_owner-fix-accounting-of-pages-when-migrating +++ a/mm/page_owner.c @@ -366,9 +366,12 @@ void __split_page_owner(struct page *pag void __folio_copy_owner(struct folio *newfolio, struct folio *old) { + int i; struct page_ext *old_ext; struct page_ext *new_ext; struct page_owner *old_page_owner; + struct page_owner *new_page_owner; + depot_stack_handle_t migrate_handle; old_ext = page_ext_get(&old->page); if (unlikely(!old_ext)) @@ -381,6 +384,8 @@ void __folio_copy_owner(struct folio *ne } old_page_owner = get_page_owner(old_ext); + new_page_owner = get_page_owner(new_ext); + migrate_handle = new_page_owner->handle; __update_page_owner_handle(new_ext, old_page_owner->handle, old_page_owner->order, old_page_owner->gfp_mask, old_page_owner->last_migrate_reason, @@ -395,6 +400,16 @@ void __folio_copy_owner(struct folio *ne old_page_owner->free_pid, old_page_owner->free_tgid, old_page_owner->free_ts_nsec); + /* + * We linked the original stack to the new folio, we need to do the same + * for the new one and the old folio otherwise there will be an imbalance + * when subtracting those pages from the stack. + */ + for (i = 0; i < (1 << new_page_owner->order); i++) { + old_page_owner->handle = migrate_handle; + old_ext = page_ext_next(old_ext); + old_page_owner = get_page_owner(old_ext); + } page_ext_put(new_ext); page_ext_put(old_ext); _ Patches currently in -mm which might be from osalvador@suse.de are mmpage_owner-update-metadata-for-tail-pages.patch mmpage_owner-fix-refcount-imbalance.patch mmpage_owner-fix-accounting-of-pages-when-migrating.patch mmpage_owner-fix-printing-of-stack-records.patch