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smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=OBWGHeLj; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B13D2606A321; Fri, 13 Nov 2026 09:51:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=OBWGHeLj Received: by smtp.kernel.org (Postfix) with ESMTPSA id 932A81F000C4; Fri, 13 Nov 2026 09:50:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794563461; bh=gRQOcYVLYl+C1cjG0ifST8FfIE974oDInNoO7fKrBgs=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=OBWGHeLjiICUmUa+HiT1ssx+8Uqlo1phTos0ZuTHvWmR/8/Ch5AvBYfwMF3bzrp7F aPo4ly43nFqtLorXsJCdMpVgEBYgPlSGOgmmx1dXHKBrb9rOCrdu/zgocxUmyjvYRV tMrigyURtbFnaXyl1O4smlP5IhBqEi5GiLnZCgtYUhIOJpx90sJdqPNp7V8jonhk3t 3bAmeBciurMykgS41aAGm569izU3WBZQLrjeHhDvKcaHJW9Qt2M7o4MOwbL3aQ9fF6 McmRjbyDbZvugNbnszeXCS6/Xm2ZHT3+P2pY5yUaIhwvm+lsr2BXF5oSiOoaThzBDj IVEnBsmW5nhKg== Message-ID: <1707907e-2261-4d3b-87fb-3dfc662e0347@kernel.org> Date: Fri, 13 Nov 2026 10:50:57 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] zram: Avoid duplicate slots in batched writeback To: Andrew Morton , Sergey Senozhatsky Cc: Jens Axboe , raoxu , minchan@kernel.org, linux-kernel@vger.kernel.org, linux-block@vger.kernel.org References: <20261112232621.6e8916a6e92bbb1afeb1e2a3@linux-foundation.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/13/26 08:26, Andrew Morton wrote: > On Tue, 10 Nov 2026 15:40:13 +0900 Sergey Senozhatsky wrote: > >> On (26/11/10 14:18), raoxu wrote: >>> The writeback interface accepts multiple page_index and page_indexes >>> parameters in one operation. Their ranges can overlap, but >>> scan_slots_for_writeback() only excludes slots that are already being >>> written back or marked as same-filled. >>> >>> A slot selected by an earlier range is placed on the post-processing list >>> and marked with ZRAM_PP_SLOT. Without checking that flag, an overlapping >>> range can enqueue the same slot again and submit it for writeback more >>> than once. >>> >>> Skip slots already marked ZRAM_PP_SLOT while holding the slot lock. This >>> keeps each slot in a writeback scan session represented by at most one >>> post-processing entry and leaves the existing release and reuse paths >>> unchanged. >>> >>> Signed-off-by: Xu Rao >> >> LGTM. >> Reviewed-by: Sergey Senozhatsky >> >> Jens, do you want to pick it up and route via block tree or should >> we route via "more traditional" tree (Andrew's tree)? > > I grabbed it. > > I did recently attempt to pull zram out of the mm project, by moving it > from mm.git's mm-unstable branch and into mm.git's mm-nonmm-unstable > branch. Because "why does the mm project contain a block device > driver". > > I undid that change after about a week - it didn't work out because > zram is joined at the hip with mm/zsmalloc.c. zsmalloc is also used by > mm/zswap.c. Are there cleaner ways of isolating both things? Like, many drivers use kmalloc() etc, and they are not part of core-mm :) -- Cheers, David