Messages in this thread | | | From | Serge Kosyrev <> | Subject | Fun with looping binds over proc | Date | Thu, 30 Oct 2014 15:07:37 +0300 |
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Good day!
First, let me show how it looks and feels on my system:
[deepfire@andromedae:~/repro-kernel-loop-mount]$ uname -a Linux andromedae 3.14.22 #1-NixOS SMP Thu Jan 1 00:00:01 UTC 1970 x86_64 GNU/Linux
[deepfire@andromedae:~/repro-kernel-loop-mount]$ ls repro.sh
[deepfire@andromedae:~/repro-kernel-loop-mount]$ cat repro.sh #!/bin/sh
test -d dir/rec || mkdir -p dir/rec test -d dir/proc || mkdir -p dir/proc mount --bind . dir/rec mount --make-private --make-unbindable dir/rec mount none -t proc dir/proc umount dir/rec umount dir/proc
[deepfire@andromedae:~/repro-kernel-loop-mount]$ time sudo ./repro.sh
real 0m0.045s user 0m0.012s sys 0m0.007s
[deepfire@andromedae:~/repro-kernel-loop-mount]$ time sudo ./repro.sh
real 0m0.035s user 0m0.009s sys 0m0.009s
[deepfire@andromedae:~/repro-kernel-loop-mount]$ time sudo ./repro.sh
real 0m0.042s user 0m0.012s sys 0m0.010s
[deepfire@andromedae:~/repro-kernel-loop-mount]$ time sudo ./repro.sh
real 0m0.039s user 0m0.013s sys 0m0.011s
[deepfire@andromedae:~/repro-kernel-loop-mount]$ time sudo ./repro.sh
real 0m0.043s user 0m0.009s sys 0m0.011s
[deepfire@andromedae:~/repro-kernel-loop-mount]$ time sudo ./repro.sh
real 0m0.048s user 0m0.011s sys 0m0.013s
[deepfire@andromedae:~/repro-kernel-loop-mount]$ time sudo ./repro.sh
real 0m0.052s user 0m0.016s sys 0m0.012s
[deepfire@andromedae:~/repro-kernel-loop-mount]$ time sudo ./repro.sh
real 0m0.059s user 0m0.008s sys 0m0.031s
[deepfire@andromedae:~/repro-kernel-loop-mount]$ time sudo ./repro.sh
real 0m0.067s user 0m0.005s sys 0m0.042s
[deepfire@andromedae:~/repro-kernel-loop-mount]$ time sudo ./repro.sh
real 0m0.116s user 0m0.011s sys 0m0.088s
[deepfire@andromedae:~/repro-kernel-loop-mount]$ time sudo ./repro.sh
real 0m0.291s user 0m0.009s sys 0m0.262s
[deepfire@andromedae:~/repro-kernel-loop-mount]$ time sudo ./repro.sh
real 0m0.857s user 0m0.011s sys 0m0.819s
[deepfire@andromedae:~/repro-kernel-loop-mount]$ time sudo ./repro.sh
real 0m1.710s user 0m0.012s sys 0m1.634s
[deepfire@andromedae:~/repro-kernel-loop-mount]$ time sudo ./repro.sh
real 0m3.186s user 0m0.010s sys 0m3.023s
[deepfire@andromedae:~/repro-kernel-loop-mount]$ time sudo ./repro.sh
real 0m6.732s user 0m0.013s sys 0m6.032s
[deepfire@andromedae:~/repro-kernel-loop-mount]$ time sudo ./repro.sh
real 0m14.541s user 0m0.008s sys 0m12.115s
* * *
Some extra data points:
1. Exchanging the two umounts results in expected behavior 2. Exchanging the two umounts absolves the need in 'mount --make-private --make-unbindable dir/rec' 3. I don't see it on 3.12.something Ubuntu kernels
-- regards, Серёга Косырев -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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