[PATCH 00/10] reduce stack footprint printing bdev names

From: Anton Suvorov
Date: Wed Jun 02 2021 - 11:34:12 EST

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Dmitry Monakhov <dmtrmonakhov@xxxxxxxxxxxxxx> started "kernel newbies"
initiative at Yandex allowing developers unfamiliar with kernel
development process to join kernel development. Initiative includes easy
to fix bugs and some small improvments. This patchset was tailored as part
of the initiative.

Few years ago Dmitry Monakhov introduced %pg formatter for vsprintf()
(https://lore.kernel.org/lkml/1428928300-9132-1-git-send-email-dmonakhov@xxxxxxxxxx/)
and switched some hot code paths to it instead of allocating temporary
buffer for device name on stack. This patchset continues his work and
expands to most places where temporary buffer with BDEVNAME_SIZE size
allocated on stack. There are also some changes in printk() calls
advised by checkpatch.pl script.

The patchset shows significant reduce of stack footprint:

./block/blk-core.c submit_bio_checks 248 112 -136
./block/blk-lib.c __blkdev_issue_discard 240 104 -136
./block/blk-settings.c disk_stack_limits 256 192 -64
./block/partitions/amiga.c amiga_partition 424 368 -56
./block/partitions/sgi.c sgi_partition 352 288 -64
./block/partitions/sun.c sun_partition 392 328 -64
./drivers/block/drbd/drbd_req.c drbd_report_io_error 200 72 -128
./drivers/block/pktcdvd.c pkt_seq_show 288 224 -64
./drivers/block/pktcdvd.c pkt_setup_dev 272 136 -136
./drivers/block/pktcdvd.c pkt_submit_bio 288 224 -64
./drivers/dax/super.c __bdev_dax_supported 192 56 -136
./drivers/dax/super.c __generic_fsdax_supported 344 280 -64
./drivers/md/dm-cache-target.c cache_ctr 392 328 -64
./drivers/md/dm-cache-target.c cache_io_hints 208 72 -136
./drivers/md/dm-clone-target.c clone_ctr 416 352 -64
./drivers/md/dm-clone-target.c clone_io_hints 216 80 -136
./drivers/md/dm-crypt.c crypt_convert_block_aead 408 272 -136
./drivers/md/dm-crypt.c kcryptd_async_done 192 56 -136
./drivers/md/dm-integrity.c integrity_metadata 872 808 -64
./drivers/md/dm-mpath.c parse_priority_group 368 304 -64
./drivers/md/dm-table.c device_area_is_invalid 216 80 -136
./drivers/md/dm-table.c dm_set_device_limits 200 72 -128
./drivers/md/dm-thin.c pool_io_hints 216 80 -136
./drivers/md/md-linear.c linear_make_request 248 112 -136
./drivers/md/md-multipath.c multipath_end_request 232 96 -136
./drivers/md/md-multipath.c multipath_error 208 72 -136
./drivers/md/md-multipath.c multipathd 248 112 -136
./drivers/md/md-multipath.c print_multipath_conf 208 64 -144
./drivers/md/md.c autorun_devices 312 184 -128
./drivers/md/md.c export_rdev 168 32 -136
./drivers/md/md.c md_add_new_disk 280 80 -200
./drivers/md/md.c md_import_device 200 56 -144
./drivers/md/md.c md_integrity_add_rdev 192 56 -136
./drivers/md/md.c md_ioctl 560 496 -64
./drivers/md/md.c md_reload_sb 224 88 -136
./drivers/md/md.c md_run 408 288 -120
./drivers/md/md.c md_seq_show 232 96 -136
./drivers/md/md.c md_update_sb 304 168 -136
./drivers/md/md.c read_disk_sb 184 48 -136
./drivers/md/md.c super_1_load 392 192 -200
./drivers/md/md.c super_90_load 304 112 -192
./drivers/md/md.c unbind_rdev_from_array 200 64 -136
./drivers/md/raid0.c create_strip_zones 400 200 -200
./drivers/md/raid0.c dump_zones 536 464 -72
./drivers/md/raid1.c fix_read_error 352 288 -64
./drivers/md/raid1.c print_conf 224 80 -144
./drivers/md/raid1.c raid1_end_read_request 216 80 -136
./drivers/md/raid1.c raid1_error 216 96 -120
./drivers/md/raid1.c sync_request_write 344 208 -136
./drivers/md/raid10.c fix_read_error 392 320 -72
./drivers/md/raid10.c print_conf 216 72 -144
./drivers/md/raid10.c raid10_end_read_request 216 80 -136
./drivers/md/raid10.c raid10_error 216 80 -136
./drivers/md/raid5-cache.c r5l_init_log 224 88 -136
./drivers/md/raid5-ppl.c ppl_do_flush 256 136 -120
./drivers/md/raid5-ppl.c ppl_flush_endio 192 56 -136
./drivers/md/raid5-ppl.c ppl_modify_log 192 56 -136
./drivers/md/raid5-ppl.c ppl_recover_entry 1296 1232 -64
./drivers/md/raid5-ppl.c ppl_submit_iounit_bio 192 56 -136
./drivers/md/raid5-ppl.c ppl_validate_rdev 184 48 -136
./drivers/md/raid5.c print_raid5_conf 208 64 -144
./drivers/md/raid5.c raid5_end_read_request 272 128 -144
./drivers/md/raid5.c raid5_error 216 80 -136
./drivers/md/raid5.c setup_conf 360 296 -64
./drivers/target/target_core_iblock.c iblock_show_configfs_dev_params 192 56 -136
./fs/block_dev.c __blkdev_put 224 80 -144
./fs/ext4/page-io.c ext4_end_bio 224 88 -136
./security/loadpin/loadpin.c loadpin_read_file 200 56 -144

Patchset was tested with kvm-xfstests -c 4k full using
https://github.com/tytso/xfstests-bld/blob/master/kernel-configs/x86_64-config-5.10
kernel config:
-------------------- Summary report
KERNEL: kernel 5.13.0-rc4-next-20210601-xfstests-00001-gf10818e9d103 #8 SMP Tue Jun 1 19:52:19 MSK 2021 x86_64
CMDLINE: -c 4k full
CPUS: 2
MEM: 1961.41

ext4/4k: 537 tests, 45 skipped, 5331 seconds
Totals: 492 tests, 45 skipped, 0 failures, 0 errors, 5281s

FSTESTVER: blktests 4bc88ef (Sun, 7 Mar 2021 12:38:37 -0800)
FSTESTVER: fio fio-3.26 (Mon, 8 Mar 2021 17:44:38 -0700)
FSTESTVER: fsverity v1.3-2-gcf8fa5e (Wed, 24 Feb 2021 13:32:36 -0800)
FSTESTVER: ima-evm-utils v1.3.2 (Wed, 28 Oct 2020 13:18:08 -0400)
FSTESTVER: nvme-cli v1.13 (Tue, 20 Oct 2020 16:50:31 -0700)
FSTESTVER: quota v4.05-40-g25f16b1 (Tue, 16 Mar 2021 17:57:19 +0100)
FSTESTVER: util-linux v2.36.2 (Fri, 12 Feb 2021 14:59:56 +0100)
FSTESTVER: xfsprogs v5.11.0 (Fri, 12 Mar 2021 15:05:13 -0500)
FSTESTVER: xfstests linux-v3.8-3068-g4072b9d3 (Mon, 5 Apr 2021 15:44:33 -0400)
FSTESTVER: xfstests-bld 4ec07f9 (Mon, 12 Apr 2021 23:49:18 -0400)
FSTESTCFG: 4k
FSTESTSET: -g auto
FSTESTOPT: aex

Anton Suvorov (10):
drbd: reduce stack footprint in drbd_report_io_error()
dax: reduce stack footprint dealing with block device names
raid-md: reduce stack footprint dealing with block device names
dm: reduce stack footprint dealing with block device names
block: reduce stack footprint dealing with block device names
target: reduce stack footprint in iblock_show_configfs_dev_params()
vfs: reduce stack footprint in __blkdev_put()
ext4: reduce stack footprint in ext4_end_bio()
security: reduce stack footprint in loadpin_read_file()
block: remove unused symbol bio_devname()

block/bio.c | 6 --
block/blk-core.c | 12 +--
block/blk-lib.c | 5 +-
block/blk-settings.c | 7 +-
block/partitions/amiga.c | 13 ++-
block/partitions/sgi.c | 5 +-
block/partitions/sun.c | 5 +-
drivers/block/drbd/drbd_req.c | 12 +--
drivers/block/pktcdvd.c | 15 ++-
drivers/dax/super.c | 34 +++----
drivers/md/dm-cache-target.c | 10 +-
drivers/md/dm-clone-target.c | 10 +-
drivers/md/dm-crypt.c | 6 +-
drivers/md/dm-integrity.c | 4 +-
drivers/md/dm-mpath.c | 6 +-
drivers/md/dm-table.c | 34 +++----
drivers/md/dm-thin.c | 8 +-
drivers/md/md-linear.c | 5 +-
drivers/md/md-multipath.c | 24 ++---
drivers/md/md.c | 146 ++++++++++++----------------
drivers/md/raid0.c | 28 +++---
drivers/md/raid1.c | 25 ++---
drivers/md/raid10.c | 66 +++++--------
drivers/md/raid5-cache.c | 5 +-
drivers/md/raid5-ppl.c | 41 ++++----
drivers/md/raid5.c | 39 ++++----
drivers/target/target_core_iblock.c | 5 +-
fs/block_dev.c | 6 +-
fs/ext4/page-io.c | 5 +-
include/linux/bio.h | 2 -
security/loadpin/loadpin.c | 5 +-
31 files changed, 242 insertions(+), 352 deletions(-)

--
2.25.1

Next message: Jaegeuk Kim: "Re: [f2fs-dev] [PATCH v6] f2fs: compress: add compress_inode to cache compressed blocks"
Previous message: Anton Suvorov: "[PATCH 05/10] block: reduce stack footprint dealing with block device names"
Next in thread: Anton Suvorov: "[PATCH 06/10] target: reduce stack footprint in iblock_show_configfs_dev_params()"
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