Re: [Bug 215323] New: Frequently swapping, userspace program will abnormally exit.

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On Mon, 13 Dec 2021 16:38:44 +0000 bugzilla-daemon@bugzilla.kernel.org wrote:

https://bugzilla.kernel.org/show_bug.cgi?id=215323

Thanks.

            Bug ID: 215323
           Summary: Frequently swapping, userspace program will abnormally
                    exit.

Looks like a zram data corruption.

           Product: Memory Management
           Version: 2.5
    Kernel Version: Linux 5.15.6
          Hardware: Intel
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Other
          Assignee: akpm@linux-foundation.org
          Reporter: dengchangcheng2021@163.com
        Regression: No

Are you sure "No"?  Did previous kernels do this, or only 5.15?

kernel: 5.15.6  version kernel
config: using x86_64_defconfig plus docker and zram configurations

# free -m
              total        used        free      shared  buff/cache   available
Mem:           3868        3560          37           3         270          42
Swap:          3868        1819        2049

Userspace program(for example dockerd) had a big chance to exit abnormally when
frequently swapping with zram in about an hour. We found that a page on the
stack of the program is cleaned to zero. In order to find out who cleans stack,
we add a monitor to catch whether a page is modifed by swap. And we found out a
page is indeed modifed after swap out/in.

To reproduce, do the following.
At first, set the value of /proc/sys/vm/swappiness to 100. 
Then use programs that include mmap or malloc to consume memory, so that to
trigger swap frequently occurs.
Finally, use docker to load images in multiple ways.
After running for a while, dockerd will exit. At the same time dockerd will
record the following:
runtime: unexpected return pc for 2021-12-09T03:32:30.290948+00:00 (none) 
dockerd[350]: time="2021-12-09T03:32:30.290846695Z" level=info msg="Applied 
tar sha256:d69d9fecbe66f52f6ba42cf251286a8912d80c20938e25620654a87e5760ccae 
to cca4b9df0747f37898e41bd2059d1a38fdf57c24b31bd00e248e2ba6cd03d63d, size:
10565287"
runtime.gopark called from 0x0
stack: frame={sp:0xc4202c1dd8, fp:0xc4202c1df8}
stack=[0xc4202c1800,0xc4202c2000)
000000c4202c1cd8:  0000000000000000  0000000000000000
000000c4202c1ce8:  0000000000000000  0000000000000000
000000c4202c1cf8:  0000000000000000  0000000000000000
000000c4202c1d08:  0000000000000000  0000000000000000
000000c4202c1d18:  0000000000000000  0000000000000000
000000c4202c1d28:  0000000000000000  0000000000000000
000000c4202c1d38:  0000000000000000  0000000000000000
000000c4202c1d48:  0000000000000000  0000000000000000
000000c4202c1d58:  0000000000000000  0000000000000000
000000c4202c1d68:  0000000000000000  0000000000000000
000000c4202c1d78:  0000000000000000  0000000000000000
000000c4202c1d88:  0000000000000000  0000000000000000
000000c4202c1d98:  0000000000000000  0000000000000000
000000c4202c1da8:  0000000000000000  0000000000000000
000000c4202c1db8:  0000000000000000  0000000000000000
000000c4202c1dc8:  0000000000000000  0000000000000000
000000c4202c1dd8: <0000000000000000  0000000000000000
000000c4202c1de8:  0000000000000000 !0000000000000000
000000c4202c1df8: >0000000000000000  0000000000000000
000000c4202c1e08:  0000000000000000  0000000000000000
000000c4202c1e18:  0000000000000000  0000000000000000
000000c4202c1e28:  0000000000000000  0000000000000000
000000c4202c1e38:  0000000000000000  0000000000000000
000000c4202c1e48:  0000000000000000  0000000000000000
000000c4202c1e58:  0000000000000000  0000000000000000
000000c4202c1e68:  0000000000000000  0000000000000000
000000c4202c1e78:  0000000000000000  0000000000000000
000000c4202c1e88:  0000000000000000  0000000000000000
000000c4202c1e98:  0000000000000000  0000000000000000
000000c4202c1ea8:  0000000000000000  0000000000000000
000000c4202c1eb8:  0000000000000000  0000000000000000
000000c4202c1ec8:  0000000000000000  0000000000000000
000000c4202c1ed8:  0000000000000000  0000000000000000
000000c4202c1ee8:  0000000000000000  0000000000000000
fatal error: unknown caller pc

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