daemon: retry secrets dir remount on transient EBUSY#52235
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thaJeztah merged 1 commit intomoby:masterfrom Apr 16, 2026
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daemon: retry secrets dir remount on transient EBUSY#52235thaJeztah merged 1 commit intomoby:masterfrom
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Thanks!
Looks good, some input on the timing though
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Thanks @firecow! Looks good, one thing remaining though - could you please rebase your branch on top of master and squash your commit into one? |
On busy Docker hosts, the read-only remount of the secrets/configs tmpfs can fail with EBUSY when the mount is momentarily held by another process immediately after writing secret/config files. This is particularly common with Swarm services using start-first update order, where old and new containers coexist on the same node. Retry the remount up to 5 times with progressive backoff (10ms + retry * 25ms). Only EBUSY triggers a retry; other errors fail immediately. Fixes moby#48783 Signed-off-by: Mads Jon Nielsen <madsjon@gmail.com>
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windows failures are unrelated. |
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- What I did
Added retry logic to
remountSecretDirfor transientEBUSYerrors when remounting the secrets/configs tmpfs as read-only.- How I did it
Wrapped the
mount.Mount("tmpfs", dir, "tmpfs", "remount,ro,...")call in a retry loop (up to 5 attempts, 100ms apart). OnlyEBUSYtriggers a retry; other errors fail immediately. A debug-level log is emitted on each retry for observability.This follows the existing retry-on-EBUSY pattern from
EnsureRemoveAllindaemon/internal/containerfs/rm.go.- How to verify it
update_config: { order: start-first }and Docker configsEBUSYrace during secrets remount should now be retried instead of failing the container startThe issue is a race condition that occurs intermittently on busy hosts, so verification requires a loaded environment. See #48783 for reproduction details.
- Description
The race condition in
remountSecretDirhas existed for a long time, but became noticeably worse after the containerd v1.7 → v2.x bump (Docker 28.x/29.x). The major containerd upgrade appears to have changed container lifecycle timing enough to widen the window where the tmpfs mount is held during secret/config setup, making theEBUSYcollision significantly more likely on busy hosts. We observe this consistently on Docker 29.3.0 (containerd v2.2.1) but not on Docker 27.5.0 (containerd v1.7.25) with comparable workloads (~100 containers).- Human readable description for the release notes
Fixes #48783
Signed-off-by: Mads Jon Nielsen madsjon@gmail.com