On Fri, Mar 03, 2023 at 01:45:48PM -0800, Luis Chamberlain wrote:
>
> You'd hope most of it is left to FS + MM, but I'm not yet sure that's
> quite it yet. Initial experimentation shows just enabling > PAGE_SIZE
> physical & logical block NVMe devices gets brought down to 512 bytes.
> That seems odd to say the least. Would changing this be an issue now?
I think you're talking about removing this part:
---
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index c2730b116dc68..2c528f56c2973 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1828,17 +1828,7 @@ static void nvme_update_disk_info(struct gendisk *disk,
unsigned short bs = 1 << ns->lba_shift;
u32 atomic_bs, phys_bs, io_opt = 0;
- /*
- * The block layer can't support LBA sizes larger than the page size
- * yet, so catch this early and don't allow block I/O.
- */
- if (ns->lba_shift > PAGE_SHIFT) {
- capacity = 0;
- bs = (1 << 9);
- }
-
blk_integrity_unregister(disk);
-
atomic_bs = phys_bs = bs;
if (id->nabo == 0) {
/*
--
This is what happens today if the driver were to let the disk create with its
actual size (testing 8k LBA size on x86):
BUG: kernel NULL pointer dereference, address: 0000000000000008
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] SMP
CPU: 10 PID: 115 Comm: kworker/u32:2 Not tainted 6.2.0-00032-gdb7183e3c314-dirty #105
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
Workqueue: nvme-wq nvme_scan_work
RIP: 0010:create_empty_buffers+0x24/0x240
Code: 66 0f 1f 44 00 00 0f 1f 44 00 00 41 54 49 89 d4 ba 01 00 00 00 55 53 48 89 fb e8 17 f5 ff ff 48 89 c5 48 89 c2 eb 03 48 89 ca <48> 8b 4a 08 4c 09 22 48 85 c9 75 f1 48 89 6a 08 48 8b 43 18 48 8d
RSP: 0000:ffffc900004578f0 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffffea0000152580 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffea0000152580
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000013
R10: ffff88803ecb6c18 R11: 0000000000000000 R12: 0000000000000000
R13: ffffea0000152580 R14: 0000000000100cc0 R15: ffff888017030288
FS: 0000000000000000(0000) GS:ffff88803ec80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000008 CR3: 0000000002c2a001 CR4: 0000000000770ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
<TASK>
? blkdev_readahead+0x20/0x20
create_page_buffers+0x79/0x90
block_read_full_folio+0x58/0x410
? blkdev_write_begin+0x20/0x20
? xas_store+0x56/0x5b0
? xas_load+0x8/0x40
? xa_get_order+0x51/0xe0
? __mod_memcg_lruvec_state+0x41/0x90
? blkdev_readahead+0x20/0x20
? blkdev_readahead+0x20/0x20
filemap_read_folio+0x41/0x2a0
? scan_shadow_nodes+0x30/0x30
? blkdev_readahead+0x20/0x20
? folio_add_lru+0x2d/0x40
? blkdev_readahead+0x20/0x20
do_read_cache_folio+0x103/0x420
? __switch_to_asm+0x3a/0x60
? __switch_to_asm+0x34/0x60
? get_page_from_freelist+0x735/0x1070
read_part_sector+0x2f/0xa0
read_lba+0xa2/0x150
efi_partition+0xdb/0x760
? snprintf+0x49/0x60
? is_gpt_valid.part.5+0x3f0/0x3f0
bdev_disk_changed+0x1ce/0x560
blkdev_get_whole+0x73/0x80
blkdev_get_by_dev+0x199/0x2e0
disk_scan_partitions+0x63/0xd0
device_add_disk+0x3c0/0x3d0
nvme_scan_ns+0x574/0xcc0
? nvme_scan_work+0x23a/0x3f0
nvme_scan_work+0x23a/0x3f0
process_one_work+0x1da/0x3a0
worker_thread+0x205/0x3a0
? process_one_work+0x3a0/0x3a0
kthread+0xc0/0xe0
? kthread_complete_and_exit+0x20/0x20
ret_from_fork+0x1f/0x30
</TASK>
