On 14/05/2024 11:38, Hannes Reinecke wrote:
Bvecs can be larger than a page, and the block layer handles
this just fine. So do not split by PAGE_SIZE but rather by
the max_segment_size if that happens to be larger.
Can you check scsi_debug for this series? I took this series only up to
this change, and got:
Startin[ 1.736470] ------------[ cut here ]------------
g Load [ 1.737777] WARNING: CPU: 0 PID: 52 at block/blk-merge.c:581
__blk_rq_map_sg+0x46a/0x480
Kernel Module fu[ 1.738862] Modules linked in:
se...[ 1.739370] CPU: 0 PID: 52 Comm: kworker/0:1H Not tainted
6.9.0-00002-g4eaa50af9312-dirty #2416
[ 1.740474] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014
[ 1.741809] Workqueue: kblockd blk_mq_run_work_fn
[ 1.742379] RIP: 0010:__blk_rq_map_sg+0x46a/0x480
[ 1.742939] Code: 17 fe ff ff 44 89 58 0c 48 8b 01 e9 ec fc ff ff 43
8d 3c 06 48 8b 14 24 81 ff 00 10 00 00 0f 86 af fc ff ff e9 02 f0
[ 1.743015] systemd[1]: File System Check on Root Device was skipped
because of a failed condition check (ConditionPathIsReadWrite=!/.
[ 1.745122] RSP: 0018:ff37636e4032bb90 EFLAGS: 00010212
[ 1.746419] systemd[1]: systemd-journald.service: unit configures an
IP firewall, but the local system does not support BPF/cgroup fi.
[ 1.746891] RAX: 000000000000001c RBX: 00000000000001b0 RCX:
ff28e6d8b0950a00
[ 1.747903] systemd[1]: (This warning is only shown for the first
unit using IP firewalling.)
[ 1.748549] RDX: ff7662becb4ac482 RSI: 0000000000001000 RDI:
00000000fffffffd
[ 1.749688] systemd[1]: Starting Journal Service...
[ 1.749895] RBP: ff7662becb4abf80 R08: 0000000000000000 R09:
ff28e6d880fadd40
[ 1.750965] R10: ff7662becb4ac480 R11: 0000000000000000 R12:
0000000000000000
[ 1.750966] R13: 0000000000000002 R14: 0000000000001000 R15:
ff7662becb4ac480
[ 1.750970] FS: 0000000000000000(0000) GS:ff28e6da75c00000(0000)
knlGS:0000000000000000
[ 1.750972] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1.750973] CR2: 00007f7407f19000 CR3: 0000000100f24002 CR4:
0000000000771ef0
[ 1.750974] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
[ 1.750975] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
0000000000000400
[ 1.750976] PKRU: 55555554
[ 1.750977] Call Trace:
[ 1.750984] <TASK>
[ 1.750986] ? __warn+0x7e/0x130
[ 1.750992] ? __blk_rq_map_sg+0x46a/0x480
[ 1.750994] ? report_bug+0x18e/0x1a0
[ 1.750999] ? handle_bug+0x3d/0x70
[ 1.751003] ? exc_invalid_op+0x18/0x70
[ 1.751006] ? asm_exc_invalid_op+0x1a/0x20
[ 1.751009] ? __blk_rq_map_sg+0x46a/0x480
[ 1.751012] scsi_alloc_sgtables+0xb7/0x3f0
[ 1.751019] sd_init_command+0x177/0x9d0
[ 1.751023] scsi_queue_rq+0x7c1/0xae0
[ 1.751027] blk_mq_dispatch_rq_list+0x2bc/0x7c0
[ 1.751031] __blk_mq_sched_dispatch_requests+0x409/0x5c0
[ 1.751035] blk_mq_sched_dispatch_requests+0x2c/0x60
[ 1.751037] blk_mq_run_work_fn+0x5f/0x70
[ 1.751039] process_one_work+0x149/0x360
I suspect that you would need to also change the PAGE_SIZE check in
__blk_bios_map_sg() also. However, I am not confident that the change
below is ok to begin with...
BTW, scsi_debug does use an insane max_segment_size of -1
Signed-off-by: Hannes Reinecke <hare@xxxxxxxxxx>
---
block/blk-merge.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 4e3483a16b75..570573d7a34f 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -278,6 +278,7 @@ struct bio *bio_split_rw(struct bio *bio, const struct queue_limits *lim,
struct bio_vec bv, bvprv, *bvprvp = NULL;
struct bvec_iter iter;
unsigned nsegs = 0, bytes = 0;
+ unsigned bv_seg_lim = max(PAGE_SIZE, lim->max_segment_size);
bio_for_each_bvec(bv, bio, iter) {
/*
@@ -289,7 +290,7 @@ struct bio *bio_split_rw(struct bio *bio, const struct queue_limits *lim,
if (nsegs < lim->max_segments &&
bytes + bv.bv_len <= max_bytes &&
- bv.bv_offset + bv.bv_len <= PAGE_SIZE) {
+ bv.bv_offset + bv.bv_len <= bv_seg_lim) {
nsegs++;
bytes += bv.bv_len;
} else {
