Re: [PATCH v6 1/4] mm/slub: enable debugging memory wasting of kmalloc

From: John Thomson
Date: Sun Oct 30 2022 - 15:24:02 EST

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On Tue, 13 Sep 2022, at 06:54, Feng Tang wrote:
> kmalloc's API family is critical for mm, with one nature that it will
> round up the request size to a fixed one (mostly power of 2). Say
> when user requests memory for '2^n + 1' bytes, actually 2^(n+1) bytes
> could be allocated, so in worst case, there is around 50% memory
> space waste.

I have a ralink mt7621 router running Openwrt, using the mips ZBOOT kernel, and appear to have bisected
a very-nearly-clean kernel v6.1rc-2 boot issue to this commit.
I have 3 commits atop 6.1-rc2: fix a ZBOOT compile error, use the Openwrt LZMA options,
and enable DEBUG_ZBOOT for my platform. I am compiling my kernel within the Openwrt build system.
No guarantees this is not due to something I am doing wrong, but any insight would be greatly appreciated.

On UART, No indication of the (once extracted) kernel booting:

transfer started ......................................... transfer ok, time=2.01s
setting up elf image... OK
jumping to kernel code
zimage at: 80BA4100 810D4720
Uncompressing Linux at load address 80001000
Copy device tree to address 80B96EE0
Now, booting the kernel...

Nothing follows

6edf2576a6cc ("mm/slub: enable debugging memory wasting of kmalloc") reverted, normal boot:
transfer started ......................................... transfer ok, time=2.01s
setting up elf image... OK
jumping to kernel code
zimage at: 80BA4100 810D47A4
Uncompressing Linux at load address 80001000
Copy device tree to address 80B96EE0
Now, booting the kernel...

[ 0.000000] Linux version 6.1.0-rc2 (john@john) (mipsel-openwrt-linux-musl-gcc (OpenWrt GCC 11.3.0 r19724+16-1521d5f453) 11.3.0, GNU ld (GNU Binutils) 2.37) #0 SMP Fri Oct 28 03:48:10 2022
[ 0.000000] SoC Type: MediaTek MT7621 ver:1 eco:3
[ 0.000000] printk: bootconsole [early0] enabled
[ 0.000000] CPU0 revision is: 0001992f (MIPS 1004Kc)
[ 0.000000] MIPS: machine is MikroTik RouterBOARD 760iGS
[ 0.000000] Initrd not found or empty - disabling initrd
[ 0.000000] VPE topology {2,2} total 4
[ 0.000000] Primary instruction cache 32kB, VIPT, 4-way, linesize 32 bytes.
[ 0.000000] Primary data cache 32kB, 4-way, PIPT, no aliases, linesize 32 bytes
[ 0.000000] MIPS secondary cache 256kB, 8-way, linesize 32 bytes.
[ 0.000000] Zone ranges:
[ 0.000000] Normal [mem 0x0000000000000000-0x000000000fffffff]
[ 0.000000] HighMem empty
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x0000000000000000-0x000000000fffffff]
[ 0.000000] Initmem setup node 0 [mem 0x0000000000000000-0x000000000fffffff]
[ 0.000000] percpu: Embedded 11 pages/cpu s16064 r8192 d20800 u45056
[ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 64960
[ 0.000000] Kernel command line: console=ttyS0,115200 rootfstype=squashfs,jffs2
[ 0.000000] Dentry cache hash table entries: 32768 (order: 5, 131072 bytes, linear)
[ 0.000000] Inode-cache hash table entries: 16384 (order: 4, 65536 bytes, linear)
[ 0.000000] Writing ErrCtl register=00019146
[ 0.000000] Readback ErrCtl register=00019146
[ 0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
[ 0.000000] Memory: 246220K/262144K available (7455K kernel code, 628K rwdata, 1308K rodata, 3524K init, 245K bss, 15924K reserved, 0K cma-reserved, 0K highmem)
[ 0.000000] SLUB: HWalign=32, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
[ 0.000000] rcu: Hierarchical RCU implementation.

boot continues as expected

possibly relevant config options:
grep -E '(SLUB|SLAB)' .config
# SLAB allocator options
# CONFIG_SLAB is not set
CONFIG_SLUB=y
CONFIG_SLAB_MERGE_DEFAULT=y
# CONFIG_SLAB_FREELIST_RANDOM is not set
# CONFIG_SLAB_FREELIST_HARDENED is not set
# CONFIG_SLUB_STATS is not set
CONFIG_SLUB_CPU_PARTIAL=y
# end of SLAB allocator options
# CONFIG_SLUB_DEBUG is not set

With this commit reverted: cpuinfo and meminfo

system type : MediaTek MT7621 ver:1 eco:3
machine : MikroTik RouterBOARD 760iGS
processor : 0
cpu model : MIPS 1004Kc V2.15
BogoMIPS : 586.13
wait instruction : yes
microsecond timers : yes
tlb_entries : 32
extra interrupt vector : yes
hardware watchpoint : yes, count: 4, address/irw mask: [0x0ffc, 0x0ffc, 0x0ffb, 0x0ffb]
isa : mips1 mips2 mips32r1 mips32r2
ASEs implemented : mips16 dsp mt
Options implemented : tlb 4kex 4k_cache prefetch mcheck ejtag llsc pindexed_dcache userlocal vint perf_cntr_intr_bit cdmm perf
shadow register sets : 1
kscratch registers : 0
package : 0
core : 0
VPE : 0
VCED exceptions : not available
VCEI exceptions : not available

processor : 1
cpu model : MIPS 1004Kc V2.15
BogoMIPS : 586.13
wait instruction : yes
microsecond timers : yes
tlb_entries : 32
extra interrupt vector : yes
hardware watchpoint : yes, count: 4, address/irw mask: [0x0ffc, 0x0ffc, 0x0ffb, 0x0ffb]
isa : mips1 mips2 mips32r1 mips32r2
ASEs implemented : mips16 dsp mt
Options implemented : tlb 4kex 4k_cache prefetch mcheck ejtag llsc pindexed_dcache userlocal vint perf_cntr_intr_bit cdmm perf
shadow register sets : 1
kscratch registers : 0
package : 0
core : 0
VPE : 1
VCED exceptions : not available
VCEI exceptions : not available

processor : 2
cpu model : MIPS 1004Kc V2.15
BogoMIPS : 586.13
wait instruction : yes
microsecond timers : yes
tlb_entries : 32
extra interrupt vector : yes
hardware watchpoint : yes, count: 4, address/irw mask: [0x0ffc, 0x0ffc, 0x0ffb, 0x0ffb]
isa : mips1 mips2 mips32r1 mips32r2
ASEs implemented : mips16 dsp mt
Options implemented : tlb 4kex 4k_cache prefetch mcheck ejtag llsc pindexed_dcache userlocal vint perf_cntr_intr_bit cdmm perf
shadow register sets : 1
kscratch registers : 0
package : 0
core : 1
VPE : 0
VCED exceptions : not available
VCEI exceptions : not available

processor : 3
cpu model : MIPS 1004Kc V2.15
BogoMIPS : 586.13
wait instruction : yes
microsecond timers : yes
tlb_entries : 32
extra interrupt vector : yes
hardware watchpoint : yes, count: 4, address/irw mask: [0x0ffc, 0x0ffc, 0x0ffb, 0x0ffb]
isa : mips1 mips2 mips32r1 mips32r2
ASEs implemented : mips16 dsp mt
Options implemented : tlb 4kex 4k_cache prefetch mcheck ejtag llsc pindexed_dcache userlocal vint perf_cntr_intr_bit cdmm perf
shadow register sets : 1
kscratch registers : 0
package : 0
core : 1
VPE : 1
VCED exceptions : not available
VCEI exceptions : not available

MemTotal: 249744 kB
MemFree: 211088 kB
MemAvailable: 187364 kB
Buffers: 0 kB
Cached: 8824 kB
SwapCached: 0 kB
Active: 1104 kB
Inactive: 8860 kB
Active(anon): 1104 kB
Inactive(anon): 8860 kB
Active(file): 0 kB
Inactive(file): 0 kB
Unevictable: 0 kB
Mlocked: 0 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 249744 kB
LowFree: 211088 kB
SwapTotal: 0 kB
SwapFree: 0 kB
Dirty: 0 kB
Writeback: 0 kB
AnonPages: 1192 kB
Mapped: 2092 kB
Shmem: 8824 kB
KReclaimable: 1704 kB
Slab: 9372 kB
SReclaimable: 1704 kB
SUnreclaim: 7668 kB
KernelStack: 592 kB
PageTables: 264 kB
SecPageTables: 0 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 124872 kB
Committed_AS: 14676 kB
VmallocTotal: 1040376 kB
VmallocUsed: 2652 kB
VmallocChunk: 0 kB
Percpu: 272 kB

Cheers,

--
John Thomson

Next message: Heiko Stuebner: "Re: [PATCH v1 1/2] arm: rockchip: Kconfig: remove select ARM_GLOBAL_TIMER"
Previous message: Philipp Hortmann: "Re: [PATCH v2 00/13] staging: r8188eu: clean up action frame handlers"
Next in thread: Vlastimil Babka: "Re: [PATCH v6 1/4] mm/slub: enable debugging memory wasting of kmalloc"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]