Messages in this thread | | | Date | Wed, 19 Oct 2011 12:42:15 -0700 (PDT) | From | Hugh Dickins <> | Subject | Re: kernel 3.0: BUG: soft lockup: find_get_pages+0x51/0x110 |
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On Wed, 19 Oct 2011, Linus Torvalds wrote: > On Wed, Oct 19, 2011 at 12:43 AM, Mel Gorman <mgorman@suse.de> wrote: > > > > My vote is with the migration change. While there are occasionally > > patches to make migration go faster, I don't consider it a hot path. > > mremap may be used intensively by JVMs so I'd loathe to hurt it. > > Ok, everybody seems to like that more, and it removes code rather than > adds it, so I certainly prefer it too. Pawel, can you test that other > patch (to mm/migrate.c) that Hugh posted? Instead of the mremap vma > locking patch that you already verified for your setup? > > Hugh - that one didn't have a changelog/sign-off, so if you could > write that up, and Pawel's testing is successful, I can apply it... > Looks like we have acks from both Andrea and Mel.
Yes, I'm glad to have that input from Andrea and Mel, thank you.
Here we go. I can't add a Tested-by since Pawel was reporting on the alternative patch, but perhaps you'll be able to add that in later.
I may have read too much into Pawel's mail, but it sounded like he would have expected an eponymous find_get_pages() lockup by now, and was pleased that this patch appeared to have cured that.
I've spent quite a while trying to explain find_get_pages() lockup by a missed migration entry, but I just don't see it: I don't expect this (or the alternative) patch to do anything to fix that problem. I won't mind if it magically goes away, but I expect we'll need more info from the debug patch I sent Justin a couple of days ago.
Ah, I'd better send the patch separately as "[PATCH] mm: fix race between mremap and removing migration entry": Pawel's "l" makes my old alpine setup choose quoted printable when I reply to your mail.
Hugh
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