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 7560B18F2E1; Mon, 17 Jun 2024 21:29:52 +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=1718659792; cv=none; b=N/9o86bphvLesYV5vCicCIokjc4dSEhBzJPr3OnUMr3CcIhd9BzY1bQoct2D+jGBgPBp8mwi17a1oT/jd6R01oqrHNwvGO4bjPcvn3YVYUh8k9pEWMld9pTmDBcBqhP7Ba1ReylMSM+qVp9SIEbiQfPfJHvbPpje0kp1X4FVsNU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718659792; c=relaxed/simple; bh=Ut0KAyrVV4smqcRV54hBWMF2hJaIfY47Llm6WJvhIYM=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=rCaNbX9KUG7l8gJWw8h1TX/OTAjTlZqxAfyrAdwKXEHPkHG9RQ9A7nQUf7iztSmPDYU4UpK8MB1U7zq749uA4RIBcj8v1LAfsefP5+pGf8FAExGSX7nmN5sJgXhswY57/1rj3EhwKJe1YHkN+oop+/FeIjBNFH/Lw0iehiLaUFE= 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=zmL/tEBM; 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="zmL/tEBM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AC6A4C2BD10; Mon, 17 Jun 2024 21:29:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1718659792; bh=Ut0KAyrVV4smqcRV54hBWMF2hJaIfY47Llm6WJvhIYM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=zmL/tEBMrfdGilrS36BdO+Nqc6pivOT+eFsbUpD7PzogUbAj0zq+5VJPNi6yfMJtW jOd8Fi901UZR4AUlpU6QjTv0eYjG/RXPESwadqPOcurAcyoV6Tu4uaM0Hf/dgTJOJW 9Jn2l6i4fepY3sAzeD4IDhjRVN4o5gCy1azVLd9U= Date: Mon, 17 Jun 2024 14:29:51 -0700 From: Andrew Morton To: Stephen Brennan Cc: linux-mm@kvack.org, Vlastimil Babka , "Vishal Moola (Oracle)" , Omar Sandoval , David Hildenbrand , "Matthew Wilcox (Oracle)" , Hao Ge , linux-debuggers@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4] mm: convert page type macros to enum Message-Id: <20240617142951.08a9cdc791c8edeeca50509b@linux-foundation.org> In-Reply-To: <87bk3z1f76.fsf@oracle.com> References: <20240607202954.1198180-1-stephen.s.brennan@oracle.com> <20240607212738.bf55318aebd7172fadaa11c5@linux-foundation.org> <87ikygo1yb.fsf@oracle.com> <87bk3z1f76.fsf@oracle.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-debuggers@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 17 Jun 2024 13:34:21 -0700 Stephen Brennan wrote: > >>> Fixes: 46df8e73a4a3 ("mm: free up PG_slab") > >> > >> Should we backport this into 6.9.x? > > > > Hi Andrew, > > > > Looks like commit 46df8e73a4a3 ("mm: free up PG_slab") is introduced in > > the v6.10-rc's, and not backported to 6.9. So PG_slab is still part of > > Hi Andrew, > > I saw that you've merged this into mm-unstable, thank you! > > Since 46df8e73a4a3 ("mm: free up PG_slab") is part of the current 6.10 > RC, it would be great if this patch could be part of the 6.10 release so > we don't release a kernel missing the PG_slab info. > > Can you confirm if mm-unstable will get merged in this release cycle? Or > else, would it be possible to include it in a branch that will? Turns out the patch as sent was based on David's "mm: allow reuse of the lower 16 bit of the page type with an actual type", which changed the page flags a lot, I redid this patch thusly: --- a/include/linux/page-flags.h~mm-convert-page-type-macros-to-enum +++ a/include/linux/page-flags.h @@ -944,15 +944,22 @@ PAGEFLAG_FALSE(HasHWPoisoned, has_hwpois * mistaken for a page type value. */ -#define PAGE_TYPE_BASE 0xf0000000 -/* Reserve 0x0000007f to catch underflows of _mapcount */ -#define PAGE_MAPCOUNT_RESERVE -128 -#define PG_buddy 0x00000080 -#define PG_offline 0x00000100 -#define PG_table 0x00000200 -#define PG_guard 0x00000400 -#define PG_hugetlb 0x00000800 -#define PG_slab 0x00001000 +enum pagetype { + /* + * Reserve 0xffff0000 - 0xfffffffe to catch _mapcount underflows and + * allow owners that set a type to reuse the lower 16 bit for their own + * purposes. + */ + PG_buddy = 0x00000080, + PG_offline = 0x00000100, + PG_table = 0x00000200, + PG_guard = 0x00000400, + PG_hugetlb = 0x00000800, + PG_slab = 0x00001000, + + PAGE_TYPE_BASE = 0xf0000000, + PAGE_MAPCOUNT_RESERVE = -128, +}; #define PageType(page, flag) \ ((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE) _ (please check carefully) and David's later "mm: allow reuse of the lower 16 bit of the page type with an actual type" becomes include/linux/mm_types.h | 5 +++++ include/linux/page-flags.h | 16 ++++++++-------- 2 files changed, 13 insertions(+), 8 deletions(-) --- a/include/linux/mm_types.h~mm-allow-reuse-of-the-lower-16-bit-of-the-page-type-with-an-actual-type +++ a/include/linux/mm_types.h @@ -157,6 +157,11 @@ struct page { * * See page-flags.h for a list of page types which are currently * stored here. + * + * Owners of typed folios may reuse the lower 16 bit of the + * head page page_type field after setting the page type, + * but must reset these 16 bit to -1 before clearing the + * page type. */ unsigned int page_type; --- a/include/linux/page-flags.h~mm-allow-reuse-of-the-lower-16-bit-of-the-page-type-with-an-actual-type +++ a/include/linux/page-flags.h @@ -951,15 +951,15 @@ enum pagetype { * allow owners that set a type to reuse the lower 16 bit for their own * purposes. */ - PG_buddy = 0x00000080, - PG_offline = 0x00000100, - PG_table = 0x00000200, - PG_guard = 0x00000400, - PG_hugetlb = 0x00000800, - PG_slab = 0x00001000, + PG_buddy = 0x40000000, + PG_offline = 0x20000000, + PG_table = 0x10000000, + PG_guard = 0x08000000, + PG_hugetlb = 0x04008000, + PG_slab = 0x02000000, - PAGE_TYPE_BASE = 0xf0000000, - PAGE_MAPCOUNT_RESERVE = -128, + PAGE_TYPE_BASE = 0x80000000, + PAGE_MAPCOUNT_RESERVE = (~0x0000ffff), }; #define PageType(page, flag) \ _ and that patch's fixup becomes --- a/include/linux/page-flags.h~mm-allow-reuse-of-the-lower-16-bit-of-the-page-type-with-an-actual-type-fix +++ a/include/linux/page-flags.h @@ -955,7 +955,7 @@ enum pagetype { PG_offline = 0x20000000, PG_table = 0x10000000, PG_guard = 0x08000000, - PG_hugetlb = 0x04008000, + PG_hugetlb = 0x04000000, PG_slab = 0x02000000, PAGE_TYPE_BASE = 0x80000000, _ and "mm/zsmalloc: use a proper page type" becomes, in part, --- a/include/linux/page-flags.h~mm-zsmalloc-use-a-proper-page-type +++ a/include/linux/page-flags.h @@ -957,6 +957,7 @@ enum pagetype { PG_guard = 0x08000000, PG_hugetlb = 0x04000000, PG_slab = 0x02000000, + PG_zsmalloc = 0x01000000, PAGE_TYPE_BASE = 0x80000000, PAGE_MAPCOUNT_RESERVE = (~0x0000ffff), and the end result is identical to yesterday's mm-everything so that's all good. However I wouldn't want to send the altered version of "mm: convert page type macros to enum" into 6.10-rcX because it gets so altered by David's mm-unstable changes for the next merge window. The new version of the hotfixes patch won't have had any valid testing on its own. So I'll temporarily drop David's "mm: page_type, zsmalloc and page_mapcount_reset()" series from mm-unstable. To permit the new "mm: convert page type macros to enum" to get some linux-next exposure. David, please remind me to restore that series in a week or so?