[PATCH 0/3] kmemleak report format changes

From: Jim Cromie
Date: Tue Apr 25 2023 - 18:25:09 EST


If format changes are not /sys/** ABI violating, heres 3 minor ones:

1st strips "age <increasing>" from output. This makes the output
idempotent; unchanging until a new leak is reported.

2nd adds the backtrace.checksum to the "backtrace:" line. This lets a
user see repeats without actually reading the whole backtrace. So now
the backtrace line looks like this:

backtrace (ck 603070071): # also see below

Q: should ck be spelled crc ? it feels more communicative.

NB: with ck exposed, it becomes possible to do a "selective clear",
something like:

echo drop 603070071 > /sys/kernel/debug/kmemleak

The 3rd patch takes __init off of kmemleak_test_init(). This fixes a
bare-pointer in the 2nd line of the backtrace below, which previously
looked like:

[<00000000ef738764>] 0xffffffffc02350a2

NB: this happens still/again, after rmmod kmemleak-test.

unreferenced object 0xffff888005d9ca40 (size 32):
comm "modprobe", pid 412, jiffies 4294703300
hex dump (first 32 bytes):
00 cd d9 05 80 88 ff ff 40 cf d9 05 80 88 ff ff ........@.......
14 a7 c4 f6 7d f9 87 10 00 00 00 00 00 00 00 00 ....}...........
backtrace (ck 1354775490):
[<000000002c474f61>] kmalloc_trace+0x26/0x90
[<00000000b26599c1>] kmemleak_test_init+0x58/0x2d0 [kmemleak_test]
[<0000000044d13990>] do_one_initcall+0x43/0x210
[<00000000131bc505>] do_init_module+0x4a/0x210
[<00000000b2902890>] __do_sys_finit_module+0x93/0xf0
[<00000000673fdce2>] do_syscall_64+0x34/0x80
[<00000000357a2d80>] entry_SYSCALL_64_after_hwframe+0x46/0xb0


Jim Cromie (3):
kmemleak: drop (age <increasing>) from leak record
kmemleak: add checksum to backtrace report
kmemleak-test: drop __init to get better backtrace

mm/kmemleak.c | 8 +++-----
samples/kmemleak/kmemleak-test.c | 2 +-
2 files changed, 4 insertions(+), 6 deletions(-)

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2.40.0