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Wed, 26 Jan 2022 04:37:23 -0800 (PST) MIME-Version: 1.0 References: <20220114081542.698002137@linuxfoundation.org> <20220114081542.746291845@linuxfoundation.org> In-Reply-To: From: Jack Wang Date: Wed, 26 Jan 2022 13:37:12 +0100 Message-ID: Subject: Re: [PATCH 5.10 01/25] md: revert io stats accounting To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, stable , Guoqing Jiang , Song Liu , Guillaume Morin Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Greg Kroah-Hartman =E4=BA=8E2022=E5=B9=B41=E6= =9C=8826=E6=97=A5=E5=91=A8=E4=B8=89 12:42=E5=86=99=E9=81=93=EF=BC=9A > > On Wed, Jan 26, 2022 at 11:09:46AM +0100, Jack Wang wrote: > > Hi, > > > > Greg Kroah-Hartman =E4=BA=8E2022=E5=B9=B41= =E6=9C=8814=E6=97=A5=E5=91=A8=E4=BA=94 19:57=E5=86=99=E9=81=93=EF=BC=9A > > > > > > From: Guoqing Jiang > > > > > > commit ad3fc798800fb7ca04c1dfc439dba946818048d8 upstream. > > > > > > The commit 41d2d848e5c0 ("md: improve io stats accounting") could cau= se > > > double fault problem per the report [1], and also it is not correct t= o > > > change ->bi_end_io if md don't own it, so let's revert it. > > > > > > And io stats accounting will be replemented in later commits. > > > > > > [1]. https://lore.kernel.org/linux-raid/3bf04253-3fad-434a-63a7-20214= e38cf26@gmail.com/T/#t > > > > > > Fixes: 41d2d848e5c0 ("md: improve io stats accounting") > > > Signed-off-by: Guoqing Jiang > > > Signed-off-by: Song Liu > > > [GM: backport to 5.10-stable] > > > Signed-off-by: Guillaume Morin > > > Signed-off-by: Greg Kroah-Hartman > > > --- > > > drivers/md/md.c | 57 +++++++++++----------------------------------= ----------- > > > drivers/md/md.h | 1 > > > 2 files changed, 12 insertions(+), 46 deletions(-) > > > > > > --- a/drivers/md/md.c > > > +++ b/drivers/md/md.c > > > @@ -459,34 +459,12 @@ check_suspended: > > > } > > > EXPORT_SYMBOL(md_handle_request); > > > > > > -struct md_io { > > > - struct mddev *mddev; > > > - bio_end_io_t *orig_bi_end_io; > > > - void *orig_bi_private; > > > - unsigned long start_time; > > > - struct hd_struct *part; > > > -}; > > > - > > > -static void md_end_io(struct bio *bio) > > > -{ > > > - struct md_io *md_io =3D bio->bi_private; > > > - struct mddev *mddev =3D md_io->mddev; > > > - > > > - part_end_io_acct(md_io->part, bio, md_io->start_time); > > > - > > > - bio->bi_end_io =3D md_io->orig_bi_end_io; > > > - bio->bi_private =3D md_io->orig_bi_private; > > > - > > > - mempool_free(md_io, &mddev->md_io_pool); > > > - > > > - if (bio->bi_end_io) > > > - bio->bi_end_io(bio); > > > -} > > > - > > > static blk_qc_t md_submit_bio(struct bio *bio) > > > { > > > const int rw =3D bio_data_dir(bio); > > > + const int sgrp =3D op_stat_group(bio_op(bio)); > > > struct mddev *mddev =3D bio->bi_disk->private_data; > > > + unsigned int sectors; > > > > > > if (mddev =3D=3D NULL || mddev->pers =3D=3D NULL) { > > > bio_io_error(bio); > > > @@ -507,26 +485,21 @@ static blk_qc_t md_submit_bio(struct bio > > > return BLK_QC_T_NONE; > > > } > > > > > > - if (bio->bi_end_io !=3D md_end_io) { > > > - struct md_io *md_io; > > > - > > > - md_io =3D mempool_alloc(&mddev->md_io_pool, GFP_NOIO)= ; > > > - md_io->mddev =3D mddev; > > > - md_io->orig_bi_end_io =3D bio->bi_end_io; > > > - md_io->orig_bi_private =3D bio->bi_private; > > > - > > > - bio->bi_end_io =3D md_end_io; > > > - bio->bi_private =3D md_io; > > > - > > > - md_io->start_time =3D part_start_io_acct(mddev->gendi= sk, > > > - &md_io->part, = bio); > > > - } > > > - > > > + /* > > > + * save the sectors now since our bio can > > > + * go away inside make_request > > > + */ > > > + sectors =3D bio_sectors(bio); > > This code snip is not inside the original patch, and it's not in > > latest upstream too. > > > /* bio could be mergeable after passing to underlayer */ > > > bio->bi_opf &=3D ~REQ_NOMERGE; > > > > > > md_handle_request(mddev, bio); > > > > > > + part_stat_lock(); > > > + part_stat_inc(&mddev->gendisk->part0, ios[sgrp]); > > > + part_stat_add(&mddev->gendisk->part0, sectors[sgrp], sectors)= ; > > > + part_stat_unlock(); > > > + > > same here, this code snip is not inside the original patch, and it's > > not in latest upstream too. > > Is it a problem? Not sure, might cause some confusion regarding io stats. > > > I think would be good keep it as the upstream version. > > Can you send a revert of this commit (it is in 5.10.92), and a backport > of the correct fix? > sure, I just sent an incremental fix for the backport itself. is it ok? Thanks! > thanks, > > greg k-h