Bug 16502
Summary: | "task cp:4126 blocked for more than 120 seconds" when copying files FAT->FAT; possibly dm-crypt related | ||
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Product: | IO/Storage | Reporter: | Sami Liedes (sami.liedes) |
Component: | Block Layer | Assignee: | Jens Axboe (axboe) |
Status: | RESOLVED OBSOLETE | ||
Severity: | normal | CC: | alan |
Priority: | P1 | ||
Hardware: | All | ||
OS: | Linux | ||
Kernel Version: | 2.6.35 | Subsystem: | |
Regression: | No | Bisected commit-id: | |
Attachments: | A script to make file system writes to block after a while. |
Description
Sami Liedes
2010-08-03 19:32:44 UTC
Created attachment 27486 [details]
A script to make file system writes to block after a while.
This seems the bug that has plagued me for quite some time and now I got into compiling vanilla 2.6.35.2 AMD64 kernel and made a test case that induces this bug quite reliably. Basically it makes a crypted file system that has 2 files that are also crypted file systems through loopback device and device mapper and then reads one and writes another and after a while, if everything goes wrong, the "task x was blocked for more than 120 seconds" message with some backtraces appears in dmesg. This is also independent of used file systems but it seems that this needs an encrypted file system through loopback device on top of encrypted file system to crash somewhat reliably.
Attached a script to bring this bug out. Just give a block device that can be overwritten (like an empty USB stick) as the only parameter to this script and wait for a while (and maybe do some other disk activity too).
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