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 65B503C2C for ; Sat, 30 Mar 2024 09:16:36 +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=1711790196; cv=none; b=eaf+U1118lkHnvnMd7RuTU6h4PNARaWWaQXaRDrrUet0rldgCAAiZdTVodQvEfPIg+aMIPfyPeIeJlzRVTRTzHQ/8etCIAHyMoWvPDMHlr6R3F0PjFTRUi9Tj3gyVhfaRtkDhFcsMCITtY+Co5P/5Zsjpwa3mMRNsKxpBZKpKJ0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711790196; c=relaxed/simple; bh=p7IQwXgdmSvNeGE0lgYdvZsmVCtEOjxj54T6NflUYfk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=mWvU6Wnphr87M7MIO5IXApST9WJqSFszp4AUVORKoHvNomH5VJkSVhm7/HbYYRYYRWkWUCUf8SJfc/3zYBgOS3Bj1dz48NbE7MS9sMgNb3oBSkucmw3qAWFgaG2uvmjfW7QW7oET58Es49VvnOAFZ/5jiH8eTrFH03u00t2GSXA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=EW8qlZmK; 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="EW8qlZmK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 74C26C433F1; Sat, 30 Mar 2024 09:16:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1711790195; bh=p7IQwXgdmSvNeGE0lgYdvZsmVCtEOjxj54T6NflUYfk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=EW8qlZmK27kLUWipiBr/AjZwaGDKpcaT5Qht1vlSYnfXQFUzokgxu9WZklObw+3Pk Gn6I7MCp/O9COzzdbnS0GmaQspbUxmPcdwbeL7KzqScsMRepzieyOf7+fExIiztzEG E08L0MLZBa6N1m4ETdtvcoQdzZT4GpJe5WpkPLas= Date: Sat, 30 Mar 2024 10:16:32 +0100 From: Greg KH To: Zi Yan Cc: stable@vger.kernel.org, linux-mm@kvack.org, Charan Teja Kalla , "Matthew Wilcox (Oracle)" , David Hildenbrand , Andrew Morton , Huang Ying , Naoya Horiguchi Subject: Re: [PATCH STABLE v4.19.y] mm/migrate: set swap entry values of THP tail pages properly. Message-ID: <2024033024-degrease-untried-0594@gregkh> References: <20240306155052.118007-1-zi.yan@sent.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: <20240306155052.118007-1-zi.yan@sent.com> On Wed, Mar 06, 2024 at 10:50:52AM -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. > > This fix is stable-only, since after commit 07e09c483cbe ("mm/huge_memory: > work on folio->swap instead of page->private when splitting folio"), > subpages of a swapcached THP no longer requires the maintenance. > > Adding THPs to the swapcache was introduced in commit > 38d8b4e6bdc87 ("mm, THP, swap: delay splitting THP during swap out"), > where each subpage of a THP added to the swapcache had its own swapcache > entry and required the ->private field to point to the correct swapcache > entry. Later, when THP migration functionality was implemented in commit > 616b8371539a6 ("mm: thp: enable thp migration in generic path"), > it initially did not handle the subpages of swapcached THPs, failing to > update their ->private fields or replace the subpage pointers in the > swapcache. Subsequently, commit e71769ae5260 ("mm: enable thp migration > for shmem thp") addressed the swapcache update aspect. This patch fixes > the update of subpage ->private fields. > > Closes: https://lore.kernel.org/linux-mm/1707814102-22682-1-git-send-email-quic_charante@quicinc.com/ > Fixes: 616b8371539a ("mm: thp: enable thp migration in generic path") > Signed-off-by: Zi Yan > Acked-by: David Hildenbrand > --- > mm/migrate.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/mm/migrate.c b/mm/migrate.c > index 171573613c39..893ea04498f7 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -514,8 +514,12 @@ int migrate_page_move_mapping(struct address_space *mapping, > if (PageSwapBacked(page)) { > __SetPageSwapBacked(newpage); > if (PageSwapCache(page)) { > + int i; > + > SetPageSwapCache(newpage); > - set_page_private(newpage, page_private(page)); > + for (i = 0; i < (1 << compound_order(page)); i++) > + set_page_private(newpage + i, > + page_private(page + i)); > } > } else { > VM_BUG_ON_PAGE(PageSwapCache(page), page); > -- > 2.43.0 > > All now queued up, thanks. greg k-h