Messages in this thread | | | Date | Thu, 25 Aug 2022 11:05:48 -0400 | From | matoro <> | Subject | Re: ext4 corruption on alpha with 4.20.0-09062-gd8372ba8ce28 |
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Hello all, I know this is quite an old thread. I recently acquired some alpha hardware and have run into this exact same problem on the latest stable kernel (5.18 and 5.19). CONFIG_COMPACTION seems to be totally broken and causes userspace to be extremely unstable - random segfaults, corruption of glibc data structures, gcc ICEs etc etc - seems most noticable during tasks with heavy I/O load.
My hardware is a DS15 (Titan), so only slightly newer than the Tsunamis mentioned earlier. The problem is greatly exacerbated when using a machine-optimized kernel (CONFIG_ALPHA_TITAN) over one with CONFIG_ALPHA_GENERIC. But it still doesn't go away on a generic kernel, just pops up less often, usually very I/O heavy tasks like checking out a tag in the kernel repo.
However all of this seems to be dependent on CONFIG_COMPACTION. With this toggled off all problems disappear, regardless of other options. I tried reverting the commit 88dbcbb3a4847f5e6dfeae952d3105497700c128 mentioned earlier in the thread (the structure has moved to a different file but was otherwise the same), but it unfortunately did not make a difference.
Since this doesn't seem to have a known cause or an easy fix, would it be reasonable to just add a Kconfig dep to disable it automatically on alpha?
Thank you!
-------- Original Message -------- Subject: Re: ext4 corruption on alpha with 4.20.0-09062-gd8372ba8ce28 Date: 2019-02-21 08:29 From: Jan Kara <jack@suse.cz> To: Meelis Roos <mroos@linux.ee>
On Thu 21-02-19 01:23:50, Meelis Roos wrote: > > > First, I found out that both the problematic alphas had memory compaction and > > > page migration and bounce buffers turned on, and working alphas had them off. > > > > > > Next, turing off these options makes the problematic alphas work. > > > > OK, thanks for testing! Can you narrow down whether the problem is due to > > CONFIG_BOUNCE or CONFIG_MIGRATION + CONFIG_COMPACTION? These are two > > completely different things so knowing where to look will help. Thanks! > > Tested both. > > Just CONFIG_MIGRATION + CONFIG_COMPACTION breaks the alpha. > Just CONFIG_BOUNCE has no effect in 5 tries.
OK, so page migration is problematic. Thanks for confirmation!
Honza
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