Re: INFO: REPRODUCED: memory leak in gpio device in 6.2-rc6
From: Mirsad Goran Todorovac
Date: Wed Feb 15 2023 - 09:45:59 EST
On 15.2.2023. 11:53, Andy Shevchenko wrote:
On Tue, Feb 14, 2023 at 07:19:16PM +0100, Mirsad Goran Todorovac wrote:
On 12. 02. 2023. 15:19, Andy Shevchenko wrote:
On Wed, Feb 08, 2023 at 08:55:24PM +0100, Mirsad Goran Todorovac wrote:
On 31. 01. 2023. 10:36, Mirsad Goran Todorovac wrote:
I came across this memory leak apparently in the GPIO device driver.
It is still present in 6.2-rc6 release candidate kernel (just ran kselftest).
This is a vanilla Torvalds tree kernel with MGLRU and KMEMLEAK (obviously)
enabled.
If you think this bug is significant, I can attempt the bug bisect in the
environment that triggered it (Lenovo LENOVO_MT_10TX_BU_Lenovo_FM_V530S-07ICB)
with BIOS M22KT49A from 11/10/2022 and AlmaLinux 8.7.
Here is the /sys/kernel/debug/kmemleak output:
unreferenced object 0xffff9e67ad71f160 (size 32):
comm "gpio-sim.sh", pid 208926, jiffies 4372229685 (age 2101.564s)
hex dump (first 32 bytes):
67 70 69 6f 2d 73 69 6d 2e 30 2d 6e 6f 64 65 30 gpio-sim.0-node0
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<0000000098bf3d1b>] slab_post_alloc_hook+0x91/0x320
[<00000000da3205c5>] __kmem_cache_alloc_node+0x1bf/0x2b0
[<00000000aa51a58a>] __kmalloc_node_track_caller+0x55/0x140
[<00000000bd682ecc>] kvasprintf+0x6b/0xd0
[<00000000a3431d55>] kasprintf+0x4e/0x70
[<00000000f52d2629>] gpio_sim_device_config_live_store+0x401/0x59d [gpio_sim]
[<00000000673fc6df>] configfs_write_iter+0xcc/0x130
[<000000001d5d0829>] vfs_write+0x2b4/0x3d0
[<00000000d2336251>] ksys_write+0x61/0xe0
[<00000000f7015bb1>] __x64_sys_write+0x1a/0x20
[<000000008ac743d2>] do_syscall_64+0x58/0x80
[<000000004d7b7d50>] entry_SYSCALL_64_after_hwframe+0x63/0xcd
Sorry, but unfortunately this patch didn't fix the memleak. Please see the result:
Thank you for give a try!
No sweat. It was worth the effort.
Yeah, that's why I put that I'm skeptical, because while patch is correct per
se it wouldn't prevent the initial leakage (it seems it happens due to other
circumstances).
I must admit that is looks like hieroglyphs to me. My learning curve had not
yet reached that point of debugging memory leaks in the kernel drivers ...
root@marvin-IdeaPad-3-15ITL6:/home/marvin/linux/kernel/linux_torvalds/tools/testing/selftests/gpio# echo clear > /sys/kernel/debug/kmemleak
root@marvin-IdeaPad-3-15ITL6:/home/marvin/linux/kernel/linux_torvalds/tools/testing/selftests/gpio# time ./gpio-sim.sh
trap: SIGTERM: bad trap
1. chip_name and dev_name attributes
1.1. Chip name is communicated to user
1.2. chip_name returns 'none' if the chip is still pending
1.3. Device name is communicated to user
2. Creating and configuring simulated chips
2.1. Default number of lines is 1
2.2. Number of lines can be specified
2.3. Label can be set
2.4. Label can be left empty
2.5. Line names can be configured
2.6. Line config can remain unused if offset is greater than number of lines
2.7. Line configfs directory names are sanitized
2.8. Multiple chips can be created
2.9. Can't modify settings when chip is live
2.10. Can't create line items when chip is live
2.11. Probe errors are propagated to user-space
2.12. Cannot enable a chip without any GPIO banks
2.13. Duplicate chip labels are not allowed
2.14. Lines can be hogged
3. Controlling simulated chips
3.1. Pull can be set over sysfs
3.2. Pull can be read from sysfs
3.3. Incorrect input in sysfs is rejected
3.4. Can't write to value
4. Simulated GPIO chips are functional
4.1. Values can be read from sysfs
4.2. Bias settings work correctly
GPIO gpio-sim test PASS
real 0m1.120s
user 0m0.283s
sys 0m0.842s
root@marvin-IdeaPad-3-15ITL6:/home/marvin/linux/kernel/linux_torvalds/tools/testing/selftests/gpio# echo scan > /sys/kernel/debug/kmemleak
root@marvin-IdeaPad-3-15ITL6:/home/marvin/linux/kernel/linux_torvalds/tools/testing/selftests/gpio# cat /sys/kernel/debug/kmemleak
unreferenced object 0xffff91f019219660 (size 32):
comm "gpio-sim.sh", pid 11223, jiffies 4295028142 (age 87.304s)
hex dump (first 32 bytes):
67 70 69 6f 2d 73 69 6d 2e 30 2d 6e 6f 64 65 30 gpio-sim.0-node0
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<ffffffff86fcd408>] __kmem_cache_alloc_node+0x1d8/0x330
[<ffffffff86f4c271>] __kmalloc_node_track_caller+0x51/0xd0
[<ffffffff872fb359>] kvasprintf+0x69/0xd0
[<ffffffff872fb4ce>] kasprintf+0x4e/0x70
[<ffffffffc1864553>] gpio_sim_device_config_live_store+0x483/0x6b5 [gpio_sim]
[<ffffffff870dde9c>] configfs_write_iter+0xcc/0x130
[<ffffffff87016869>] vfs_write+0x1f9/0x3b0
[<ffffffff87016dab>] ksys_write+0x6b/0xf0
[<ffffffff87016e59>] __x64_sys_write+0x19/0x20
[<ffffffff87b91188>] do_syscall_64+0x58/0x80
[<ffffffff87c000aa>] entry_SYSCALL_64_after_hwframe+0x72/0xdc
root@marvin-IdeaPad-3-15ITL6:/home/marvin/linux/kernel/linux_torvalds/tools/testing/selftests/gpio# uname -rms
Linux 6.2.0-rc8-lru-km-andy-00015-gf6feea56f66d-dirty x86_64
root@marvin-IdeaPad-3-15ITL6:/home/marvin/linux/kernel/linux_torvalds/tools/testing/selftests/gpio#
I can verify that I build the right patch:
marvin@marvin-IdeaPad-3-15ITL6:~/linux/kernel/linux_torvalds$ git diff
diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c
index 60514bc5454f..7f79e49b23d7 100644
--- a/drivers/gpio/gpio-sim.c
+++ b/drivers/gpio/gpio-sim.c
@@ -954,9 +954,9 @@ static void gpio_sim_device_deactivate_unlocked(struct gpio_sim_device *dev)
swnode = dev_fwnode(&dev->pdev->dev);
platform_device_unregister(dev->pdev);
+ gpio_sim_remove_hogs(dev);
gpio_sim_remove_swnode_recursive(swnode);
dev->pdev = NULL;
- gpio_sim_remove_hogs(dev);
}
static ssize_t
marvin@marvin-IdeaPad-3-15ITL6:~/linux/kernel/linux_torvalds$
Alternatively, I could try to bisect if you think it's prudent to try that.
But first I need a stroll after this kernel build :-)
Do you think that knowing when the bug was introduced might help find the culprit?
--
Mirsad Todorovac
System engineer
Faculty of Graphic Arts | Academy of Fine Arts
University of Zagreb
Republic of Croatia, the European Union
Sistem inženjer
Grafički fakultet | Akademija likovnih umjetnosti
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