Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
IronPort-SDR: N3Fy8o9TJLxKDuMUbwkv4OjzSSph7S+BRjE2V7zdYJn2adzJzcDBX4SXLycv6y4LyEt2OWbWmW
 SeOrR5VmGOzopy5R8mMTDabUxSymKFUeTFGdNFRrGBF6ii6o2tDclRjaDHlHPNKe21umYjo+lN
 frOHI9k1nNlfhID9DIQe+gaQTNS5QQ/xxAz4Tn1SM9567fQN+LIxD97pxmcj6zBAZ6OOd5rxxJ
 7Rd6ejDzGJ3ZLjUyZQ9EsOVMKmgTogvJVbCV8TNUAGea48SmPWQUv3ZP0EdbEO77nPCAxmmBR8
 dyc=
From:   Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>
To:     Christoph Hellwig <hch@lst.de>
CC:     John Stultz <john.stultz@linaro.org>,
        Johannes Thumshirn <Johannes.Thumshirn@wdc.com>,
        Damien Le Moal <Damien.LeMoal@wdc.com>,
        Jens Axboe <axboe@kernel.dk>,
        David Anderson <dvander@google.com>,
        Alistair Delva <adelva@google.com>,
        Todd Kjos <tkjos@google.com>,
        Amit Pundir <amit.pundir@linaro.org>,
        YongQin Liu <yongqin.liu@linaro.org>,
        lkml <linux-kernel@vger.kernel.org>,
        "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>
Subject: Re: [REGRESSION] "split bio_kmalloc from bio_alloc_bioset" causing
 crash shortly after bootup
Thread-Topic: [REGRESSION] "split bio_kmalloc from bio_alloc_bioset" causing
 crash shortly after bootup
Thread-Index: AQHXCZD3vAo2wh9jek+o1gtQqbdo1w==
Date:   Tue, 23 Feb 2021 03:51:23 +0000
Message-ID: <BYAPR04MB4965F0B60169371A25CD423E86809@BYAPR04MB4965.namprd04.prod.outlook.com>
References: <CALAqxLUWjr2oR=5XxyGQ2HcC-TLARvboHRHHaAOUFq6_TsKXyw@mail.gmail.com>
Accept-Language: en-US
Content-Language: en-US
wdcipoutbound: EOP-TRUE
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-Network-Message-Id: 6814ea6b-1cfb-43f3-7a3e-08d8d7ae49ac
X-MS-Exchange-CrossTenant-originalarrivaltime: 23 Feb 2021 03:51:23.1747
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: b61c8803-16f3-4c35-9b17-6f65f441df86
X-MS-Exchange-CrossTenant-mailboxtype: HOSTED
X-MS-Exchange-CrossTenant-userprincipalname: 2Rl6iC7yCaYRodFPzsUjjJk8q0CcVtrJXvT42DDs0KlAPy8LCphrJJouLoT4NnwBXhVUdf+e09ExKtrJ7hmm0EHOsWLAKnxKuIUrQwltWlk=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR04MB6103
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Christoph,=0A=
=0A=
On 2/22/21 19:07, John Stultz wrote:=0A=
> [   34.785313]  bio_alloc_bioset+0x14/0x230=0A=
> [   34.796189]  bio_clone_fast+0x28/0x80=0A=
> [   34.799848]  bio_split+0x50/0xd0=0A=
> [   34.803072]  blk_crypto_fallback_encrypt_bio+0x2ec/0x5e8=0A=
> [   34.808384]  blk_crypto_fallback_bio_prep+0xfc/0x140=0A=
> [   34.813345]  __blk_crypto_bio_prep+0x13c/0x150=0A=
> [   34.817784]  submit_bio_noacct+0x3c0/0x548=0A=
> [   34.821880]  submit_bio+0x48/0x200=0A=
> [   34.825278]  ext4_io_submit+0x50/0x68=0A=
> [   34.828939]  ext4_writepages+0x558/0xca8=0A=
> [   34.832860]  do_writepages+0x58/0x108=0A=
> [   34.836522]  __writeback_single_inode+0x44/0x510=0A=
> [   34.841137]  writeback_sb_inodes+0x1e0/0x4a8=0A=
> [   34.845404]  __writeback_inodes_wb+0x78/0xe8=0A=
> [   34.849670]  wb_writeback+0x274/0x3e8=0A=
> [   34.853328]  wb_workfn+0x308/0x5f0=0A=
> [   34.856726]  process_one_work+0x1ec/0x4d0=0A=
> [   34.860734]  worker_thread+0x44/0x478=0A=
> [   34.864392]  kthread+0x140/0x150=0A=
> [   34.867618]  ret_from_fork+0x10/0x30=0A=
> [   34.871197] Code: a9ba7bfd 910003fd f9000bf3 7900bfa1 (f9403441)=0A=
> [   34.877289] ---[ end trace e6c2a3ab108278f0 ]---=0A=
> [   34.893636] Kernel panic - not syncing: Oops: Fatal exception=0A=
>=0A=
Looking at the other call sites do we need something like following ?=0A=
=0A=
diff --git a/block/bounce.c b/block/bounce.c=0A=
index fc55314aa426..f8a3656e89c3 100644=0A=
--- a/block/bounce.c=0A=
+++ b/block/bounce.c=0A=
@@ -217,6 +217,7 @@ static void bounce_end_io_read_isa(struct bio *bio)=0A=
 static struct bio *bounce_clone_bio(struct bio *bio_src, gfp_t gfp_mask,=
=0A=
                struct bio_set *bs)=0A=
 {=0A=
+       unsigned int nr_iovecs =3D bio_segments(bio_src);=0A=
        struct bvec_iter iter;=0A=
        struct bio_vec bv;=0A=
        struct bio *bio;=0A=
@@ -243,7 +244,11 @@ static struct bio *bounce_clone_bio(struct bio=0A=
*bio_src, gfp_t gfp_mask,=0A=
         *    __bio_clone_fast() anyways.=0A=
         */=0A=
 =0A=
-       bio =3D bio_alloc_bioset(gfp_mask, bio_segments(bio_src), bs);=0A=
+       if (bs)=0A=
+               bio =3D bio_alloc_bioset(gfp_mask, nr_iovecs, bs);=0A=
+       else=0A=
+               bio =3D bio_kmalloc(gfp_mask, nr_iovecs);=0A=
+=0A=
        if (!bio)=0A=
                return NULL;=0A=
        bio->bi_bdev            =3D bio_src->bi_bdev;=0A=
=0A=
Since __blk_queue_bounce() passes the NULL for the passthru case as a=0A=
bio_set value ?=0A=
=0A=