Re: INFO: REPRODUCED: memory leak in gpio device in 6.2-rc6

Bartosz Golaszewski
2023-02-16T14:17:07Z

On Wed, Feb 15, 2023 at 3:45 PM Mirsad Goran Todorovac
<mirsad.todorovac@alu.unizg.hr> wrote:
>
> 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
> Sveučilište u Zagrebu
>

Thanks for the report Mirsad, just sent out a fix.

Bart