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 E1F231E519 for ; Wed, 6 Mar 2024 13:51:37 +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=1709733098; cv=none; b=fCLqX5E7n5foN50JzRqetBuCLP2k65zmgleowUbe24iOf1iMUygbBH6a8G9PJsKry1cYrWtOlUp98xXkme6hwhV6PgmPtRO0jrwVu/ao/Z5628IDdtX9g5ABKxK0unETdvU61CInpVPQombyRVHORRZGkg4A9PiFY/FDIa0yIvc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709733098; c=relaxed/simple; bh=aiFjeCBLulfJTYlTDxGvoYCYsPSgBsu9exnZA8T53gU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=LXcytXWNDdR2hiPk6ZJcr2ryffANaWPPOLVTwU874mHPmEpFb1UFggYLdG2y+TZ0Zyrs6rHXsa0fXwQdM76XWXfx/rsqVfdurtHVXmOzaRt3Q/dXzbeXWGW4Kx4v46u+EgSM4WjUlHPMUfkz7V2mx2wXE4uEsv8DNSkGHeK/hEY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=A39kwWOI; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="A39kwWOI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 10904C433F1; Wed, 6 Mar 2024 13:51:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1709733097; bh=aiFjeCBLulfJTYlTDxGvoYCYsPSgBsu9exnZA8T53gU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=A39kwWOIlN1tTvGMCgnNtPrPW9Fv6IcBNiZI2hvUTXJozcUFomlewZYJGyyyLxKnS zJlSqf8PwyNHfST8+bRmJnmXjKVrSqXglYebU+JW24pES/McMZq7mbvRhlaLS0Iixp he8weUxWetwiKKdKoVewjeqPWSSPVwr0QcrwXoiE= Date: Wed, 6 Mar 2024 13:51:34 +0000 From: Greg KH To: Zi Yan Cc: David Hildenbrand , stable@vger.kernel.org, linux-mm@kvack.org, Charan Teja Kalla , "\"Matthew Wilcox (Oracle)\"" , Andrew Morton , Huang Ying , Naoya Horiguchi Subject: Re: [PATCH STABLE v6.1.y] mm/migrate: set swap entry values of THP tail pages properly. Message-ID: <2024030649-utilize-budding-380d@gregkh> References: <20240305161313.90954-1-zi.yan@sent.com> <2024030506-quotable-kerosene-6820@gregkh> <0910e8f0-5490-4d08-ac64-da4077a1e703@redhat.com> <2024030527-footrest-cathedral-5e15@gregkh> <075777FD-8EA9-446F-A52C-96AF43170EA7@nvidia.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <075777FD-8EA9-446F-A52C-96AF43170EA7@nvidia.com> On Tue, Mar 05, 2024 at 06:13:39PM -0500, Zi Yan wrote: > On 5 Mar 2024, at 17:32, Greg KH wrote: > > > On Tue, Mar 05, 2024 at 11:09:17PM +0100, David Hildenbrand wrote: > >> On 05.03.24 23:04, Greg KH wrote: > >>> On Tue, Mar 05, 2024 at 11:13:13AM -0500, Zi Yan wrote: > >>>> From: Zi Yan > >>>> > >>>> The tail pages in a THP can have swap entry information stored in their > >>>> private field. When migrating to a new page, all tail pages of the new > >>>> page need to update ->private to avoid future data corruption. > >>>> > >>>> Signed-off-by: Zi Yan > >>>> --- > >>>> mm/migrate.c | 6 +++++- > >>>> 1 file changed, 5 insertions(+), 1 deletion(-) > >>> > >>> What is the git commit id of this change in Linus's tree? > >> > >> Unfortunately, we had to do stable-only versions, because the backport > >> of the "accidental" fix that removes the per-subpage "private" information > >> would be non-trivial, especially for pre-folio-converison times. > >> > >> The accidental fix is > >> > >> 07e09c483cbef2a252f75d95670755a0607288f5 > > > > None of that is obvious at all here, we need loads of documentation in > > the changelog text that says all of that please. > > How about? > > Before 07e09c483cbe ("mm/huge_memory: work on folio->swap instead of > page->private when splitting folio"), when a THP is added into swapcache, > each of its subpages has its own swapcache entry and need ->private pointing > to the right swapcache entry. THP added to swapcache function is added in > 38d8b4e6bdc87 ("mm, THP, swap: delay splitting THP during swap out"). > When THP migration was added in 616b8371539a6 ("mm: thp: enable thp migration in generic path"), it did not take care of swapcached THP's subpages, > neither updated subpage's ->private nor replaced subpage pointer in > the swapcache. Later, e71769ae5260 ("mm: enable thp migration for shmem thp") > fixed swapcache update part. Now this patch fixes the subpage ->private > update part. That's better than what is there now :) So yes, please resend all of these with the new text and then we can queue them up. thanks, greg k-h