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 1E09F148841; Fri, 26 Apr 2024 15:12:43 +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=1714144364; cv=none; b=nT1TTdFwte24mvDlg3aeV5hru7VCYY0VWqIIUQIlSl7VBiDhKmqaoUkkDe+SCuINodejjX6+Ou7TPyIh+ADMVlqIKIaEgwaQb2qUChnnok83k72BK1+0N6IibC905h3JJy3vNVKVBQwMXKXs0akxhewfjl8rBJGE3u0HtAGLax8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714144364; c=relaxed/simple; bh=quc7LSiSVw2TT07uTSXycfAYUCFeYT8rW3NArklrOJQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=sse7hsad+wxHVXuvjjzDkFKpBTIpj5yXkKW5QQ9RqFfM5PjoH18OEPbA+RmWedkHFnU1z/enMVdp8T2HCQ7avprNEIy76NHlnqiNNdiK+pJZTPOCNO3M9huj18vSB3SxVzBQPFVw5o+hHBXyVerCzFDVatsLt1PyZt2/wyd8cLw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UW5Mm8BC; 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="UW5Mm8BC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9E65AC113CD; Fri, 26 Apr 2024 15:12:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1714144363; bh=quc7LSiSVw2TT07uTSXycfAYUCFeYT8rW3NArklrOJQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UW5Mm8BCg0Roek5VE0mS5z+hU4Rliru5i4lxsEb6rJbZNPG0GNrdQRtkDQxnb70A2 wmpqBhMuWvX5vGpb/2QoMAZMZy21JdccdODDRNV9qwEWubFJPpfan9sSS4Qyj24qlH 88zpKEYRbBIkLYo1GadptPit6L8NfZzsA4kDQ+N6O5EJtsfweFTlyvwJZvMmuQSMEV pmwDFrf+V1zCLYFN6Mhifq6VU5a6avVs1dtBi5wwRIRZ7u3u0EAMkIeB+2j4h9DIvw sgRikwxLLz/3cs9yEEkwnKP6YLlXjH1MHlncJkACn31uQsj5kLJVkBkjUJ2b44RNEi xdA+KkNkUUcYw== Date: Fri, 26 Apr 2024 08:12:43 -0700 From: "Darrick J. Wong" To: "Pankaj Raghav (Samsung)" Cc: willy@infradead.org, brauner@kernel.org, david@fromorbit.com, chandan.babu@oracle.com, akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org, hare@suse.de, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-xfs@vger.kernel.org, mcgrof@kernel.org, gost.dev@samsung.com, p.raghav@samsung.com Subject: Re: [PATCH v4 03/11] filemap: allocate mapping_min_order folios in the page cache Message-ID: <20240426151243.GD360919@frogsfrogsfrogs> References: <20240425113746.335530-1-kernel@pankajraghav.com> <20240425113746.335530-4-kernel@pankajraghav.com> Precedence: bulk X-Mailing-List: linux-kernel@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: <20240425113746.335530-4-kernel@pankajraghav.com> On Thu, Apr 25, 2024 at 01:37:38PM +0200, Pankaj Raghav (Samsung) wrote: > From: Luis Chamberlain > > filemap_create_folio() and do_read_cache_folio() were always allocating > folio of order 0. __filemap_get_folio was trying to allocate higher > order folios when fgp_flags had higher order hint set but it will default > to order 0 folio if higher order memory allocation fails. > > Supporting mapping_min_order implies that we guarantee each folio in the > page cache has at least an order of mapping_min_order. When adding new > folios to the page cache we must also ensure the index used is aligned to > the mapping_min_order as the page cache requires the index to be aligned > to the order of the folio. If we cannot find a folio of at least min_order size, what error is sent back? If the answer is "the same error that you get if we cannot allocate a base page today (aka ENOMEM)", then I think I understand this enough to say Reviewed-by: Darrick J. Wong --D > Signed-off-by: Luis Chamberlain > Co-developed-by: Pankaj Raghav > Signed-off-by: Pankaj Raghav > --- > mm/filemap.c | 24 +++++++++++++++++------- > 1 file changed, 17 insertions(+), 7 deletions(-) > > diff --git a/mm/filemap.c b/mm/filemap.c > index 30de18c4fd28..f0c0cfbbd134 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -858,6 +858,8 @@ noinline int __filemap_add_folio(struct address_space *mapping, > > VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); > VM_BUG_ON_FOLIO(folio_test_swapbacked(folio), folio); > + VM_BUG_ON_FOLIO(folio_order(folio) < mapping_min_folio_order(mapping), > + folio); > mapping_set_update(&xas, mapping); > > if (!huge) { > @@ -1895,8 +1897,10 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index, > folio_wait_stable(folio); > no_page: > if (!folio && (fgp_flags & FGP_CREAT)) { > - unsigned order = FGF_GET_ORDER(fgp_flags); > + unsigned int min_order = mapping_min_folio_order(mapping); > + unsigned int order = max(min_order, FGF_GET_ORDER(fgp_flags)); > int err; > + index = mapping_align_start_index(mapping, index); > > if ((fgp_flags & FGP_WRITE) && mapping_can_writeback(mapping)) > gfp |= __GFP_WRITE; > @@ -1936,7 +1940,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index, > break; > folio_put(folio); > folio = NULL; > - } while (order-- > 0); > + } while (order-- > min_order); > > if (err == -EEXIST) > goto repeat; > @@ -2425,13 +2429,16 @@ static int filemap_update_page(struct kiocb *iocb, > } > > static int filemap_create_folio(struct file *file, > - struct address_space *mapping, pgoff_t index, > + struct address_space *mapping, loff_t pos, > struct folio_batch *fbatch) > { > struct folio *folio; > int error; > + unsigned int min_order = mapping_min_folio_order(mapping); > + pgoff_t index; > > - folio = filemap_alloc_folio(mapping_gfp_mask(mapping), 0); > + folio = filemap_alloc_folio(mapping_gfp_mask(mapping), > + min_order); > if (!folio) > return -ENOMEM; > > @@ -2449,6 +2456,8 @@ static int filemap_create_folio(struct file *file, > * well to keep locking rules simple. > */ > filemap_invalidate_lock_shared(mapping); > + /* index in PAGE units but aligned to min_order number of pages. */ > + index = (pos >> (PAGE_SHIFT + min_order)) << min_order; > error = filemap_add_folio(mapping, folio, index, > mapping_gfp_constraint(mapping, GFP_KERNEL)); > if (error == -EEXIST) > @@ -2509,8 +2518,7 @@ static int filemap_get_pages(struct kiocb *iocb, size_t count, > if (!folio_batch_count(fbatch)) { > if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ)) > return -EAGAIN; > - err = filemap_create_folio(filp, mapping, > - iocb->ki_pos >> PAGE_SHIFT, fbatch); > + err = filemap_create_folio(filp, mapping, iocb->ki_pos, fbatch); > if (err == AOP_TRUNCATED_PAGE) > goto retry; > return err; > @@ -3708,9 +3716,11 @@ static struct folio *do_read_cache_folio(struct address_space *mapping, > repeat: > folio = filemap_get_folio(mapping, index); > if (IS_ERR(folio)) { > - folio = filemap_alloc_folio(gfp, 0); > + folio = filemap_alloc_folio(gfp, > + mapping_min_folio_order(mapping)); > if (!folio) > return ERR_PTR(-ENOMEM); > + index = mapping_align_start_index(mapping, index); > err = filemap_add_folio(mapping, folio, index, gfp); > if (unlikely(err)) { > folio_put(folio); > -- > 2.34.1 > >