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 C49121DED40 for ; Tue, 19 Aug 2025 10:19:35 +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=1755598775; cv=none; b=O3Y38mnB4Ypn+BftTQDc4knKYj7s6bkJgYM9FEd0gazlMXZgNy0IHxwglCLJsIzsu4XBil9G3pHPN0T+4mGRNc3l4LV1pMlYNBFQ40t2Ezm9HmVoiYqQx199xzhkCyai9wnZUZirrfj6+eIEVd2MM8ZaCOJkljg71qM8wc3KWE4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755598775; c=relaxed/simple; bh=mbWBlMvN7EuNO2CRn0xw6M90XeFQPpDtRTrW/Ontv4k=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=HNsKsx+WFV44ATfIEf2qi2RGLRqyXRafQwo/4mlstdBvYObfjQa0hCEVStksBkyyyvcBzqzeYXvjjcanBcpE3XHTqZq/acwTzvH4BlBWp/bX6g8i7FCCRWSQJzC0mrqiNlAJuxswqcS4HbdHc1fJbNowL+Smv2LbQqVKN3tPLf4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Hy9fiBTz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Hy9fiBTz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E725AC113D0; Tue, 19 Aug 2025 10:19:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755598775; bh=mbWBlMvN7EuNO2CRn0xw6M90XeFQPpDtRTrW/Ontv4k=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Hy9fiBTz6mhZ2ySufGhdtBJIFrXUaDuIRwIpl5o0G6sljcGZGxu0ixOIRUpqfu1WP 2wtJpSp/BaEx7dBamYq28Kd6GzZp4Nu1E/ni2UclS1hFq2WsRQYlRQ/D3KeSnEfgai NHuQGOy/RNVwdvuf7I1D3FVuo6tzdTFoz8baM07q16bAoLRn8w6neTQaCvdtWz/88f 9OTilLE4DFteGIRrcLY3oIZ4bwTcBRAHF7k1+OvLPTBoV7hxlt4a01jxXtelbmcn68 FwMfEjlufP4ooqCwrftfJyoGBn4ZqaLDyaMZDzhOS+Gbxcx4Y3qo42jl7M8HSEYo6d ppjPFrq4PBlEQ== Date: Tue, 19 Aug 2025 12:19:30 +0200 From: Christian Brauner To: Al Viro Cc: linux-fsdevel@vger.kernel.org, Linus Torvalds , Jan Kara , "Lai, Yi" , Tycho Andersen , Andrei Vagin , Pavel Tikhomirov Subject: Re: [PATCH 2/4] propagate_umount(): only surviving overmounts should be remounted Message-ID: <20250819-aktenordner-sensor-1d90cc27c9ea@brauner> References: <20250815233316.GS222315@ZenIV> <20250815233450.GB2117906@ZenIV> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20250815233450.GB2117906@ZenIV> On Sat, Aug 16, 2025 at 12:34:50AM +0100, Al Viro wrote: > ... as the comments in reparent() clearly say. As it is, we reparent > *all* overmounts of the mounts being taken out, including those that > are taken out themselves. It's not only a potentially massive slowdown > (on a pathological setup we might end up with O(N^2) time for N mounts > being kicked out), it can end up with incorrect ->overmount in the > surviving mounts. > > Fixes: f0d0ba19985d "Rewrite of propagate_umount()" > Signed-off-by: Al Viro > --- Reviewed-by: Christian Brauner