56 lines
1.8 KiB
Diff
56 lines
1.8 KiB
Diff
From: Cole Robinson <crobinso@redhat.com>
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Date: Thu, 26 Sep 2019 15:00:55 -0400
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Subject: [PATCH] vircgroupv2: Fix VM startup when legacy cgroups are defined
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On Fedora 31, starting a 'mock' build alters /proc/$pid/cgroup,
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probably due to usage of systemd-nspawn.
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Before:
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$ cat /proc/self/cgroup
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0::/user.slice/user-1000.slice/...
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After:
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$ cat /proc/self/cgroup
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1:name=systemd:/
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0::/user.slice/user-1000.slice/...
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The cgroupv2 code mishandles that first line in the second case, which
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causes VM startup to fail with: Unable to read from
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'/sys/fs/cgroup/machine/cgroup.controllers': No such file or directory
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The kernel docs[1] say that the cgroupv2 path will always start with
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'0::', which in the code here controllers="". Only set the v2 placement
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path when we see that cgroup file entry.
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[1] https://www.kernel.org/doc/html/v5.3/admin-guide/cgroup-v2.html#processes
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https://bugzilla.redhat.com/show_bug.cgi?id=1751120
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Signed-off-by: Cole Robinson <crobinso@redhat.com>
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---
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src/util/vircgroupv2.c | 6 +++++-
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1 file changed, 5 insertions(+), 1 deletion(-)
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diff --git a/src/util/vircgroupv2.c b/src/util/vircgroupv2.c
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index 2aca4e5d62..ecf7d42076 100644
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--- a/src/util/vircgroupv2.c
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+++ b/src/util/vircgroupv2.c
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@@ -194,12 +194,16 @@ virCgroupV2DetectMounts(virCgroupPtr group,
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static int
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virCgroupV2DetectPlacement(virCgroupPtr group,
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const char *path,
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- const char *controllers ATTRIBUTE_UNUSED,
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+ const char *controllers,
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const char *selfpath)
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{
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if (group->unified.placement)
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return 0;
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+ /* controllers="" indicates the cgroupv2 controller path */
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+ if (STRNEQ_NULLABLE(controllers, ""))
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+ return 0;
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+
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/*
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* selfpath == "/" + path="" -> "/"
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* selfpath == "/libvirt.service" + path == "" -> "/libvirt.service"
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