dump: skip POSIX timers targeting dead threads#2996
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pojntfx wants to merge 4 commits intocheckpoint-restore:criu-devfrom
Open
dump: skip POSIX timers targeting dead threads#2996pojntfx wants to merge 4 commits intocheckpoint-restore:criu-devfrom
pojntfx wants to merge 4 commits intocheckpoint-restore:criu-devfrom
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…eting a dead thread Assisted-by: Claude:claude-opus-4-6 Signed-off-by: Felicitas Pojtinger <felicitas@pojtinger.com>
… timer Assisted-by: Claude:claude-opus-4-6 Signed-off-by: Felicitas Pojtinger <felicitas@pojtinger.com>
Assisted-by: Claude:claude-opus-4-6 Signed-off-by: Felicitas Pojtinger <felicitas@pojtinger.com>
Assisted-by: Claude:claude-opus-4-6 Signed-off-by: Felicitas Pojtinger <felicitas@pojtinger.com>
pojntfx
referenced
this pull request
in loopholelabs/criu
Apr 7, 2026
…t/dead threads from checkpoint Signed-off-by: Felicitas Pojtinger <felicitas@pojtinger.com>
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What:
When a POSIX timer uses SIGEV_THREAD_ID and the target thread has exited, dump fails in PID namespaces (
Unable to convert the notify thread id) and restore fails without PID namespaces (EINVALfrom timer_create()). We noticed this when an application switched from Java 8 to Java 21.How:
To fix this, this PR detects dead notify threads during dump and skips the timer instead of failing. The kernel already silently drops signals from these timers, so skipping them during dump is safe.
Tests:
zdtm/static/dead_thread_posix_timerzdtm/static/dead_thread_posix_timer_hI added
dead_thread_posix_timer_hsince I wanted to specifically trigger the restore failure case, which needs host mode. I followed the convention thatpthread_timers.candpthread_timers_h.cuses.