On Fri, Jun 01, 2012 at 01:44:44AM -0700, Hugh Dickins wrote: > > 3f31d07571eeea18a7d34db9af21d2285b807a17 is the first bad commit > > commit 3f31d07571eeea18a7d34db9af21d2285b807a17 > > Author: Hugh Dickins <hughd@xxxxxxxxxx> > > Date: Tue May 29 15:06:40 2012 -0700 > > > > mm/fs: route MADV_REMOVE to FALLOC_FL_PUNCH_HOLE > > > > Now tmpfs supports hole-punching via fallocate(), switch madvise_remove() > > to use do_fallocate() instead of vmtruncate_range(): which extends > > madvise(,,MADV_REMOVE) support from tmpfs to ext4, ocfs2 and xfs. > > > > Hugh ? > > Ow, you've caught me. As I said in another mail, it looks like the bisect was wrong somewhere, as with this backed out I still see problems. > One half of the patch at the bottom should fix that: I'm not sure that > it's the fix we actually want (a mapping_cap_account_dirty test might > be more appropriate, but it's easier just to test a page flag here); > but it should be good to shed more light on the problem. I'll give the patch a try anyway, as builds are quick on that box. > So I'm wondering if your trinity fuzzer happens to succeed a lot more > often on madvise MADV_REMOVEs than fallocate FALLOC_FL_PUNCH_HOLEs, and > the bug you converged on is not in tmpfs, but in ext4 (or xfs? or ocfs2?), > which began to support MADV_REMOVE with that commit. ext4 is a possibility. > So the second half of the patch should show which filesystem's page is > involved when you hit the WARN_ON - unless the first half of the patch > turns out to stop the warnings completely, in which case I need to think > harder about what was going on in tmpfs, and whether it matters. > > Or another possibility is that the bad commit doesn't actually touch mm > at all: you were doing a bisection just on mm/ changes, weren't you? oh, good point. It hadn't occured to me that this could be fs related. The mm-heavy stack-trace may have misled me. > > Sometimes during the bisect these errors happened > > in pairs, sometimes only together. > > Sometimes in pairs, sometimes together? I don't understand. beware late-night emails. I meant sometimes I saw both the list-debug's and the WARN, but other times I saw only one or the other. > Please give this patch a try (preferably on current git), and let us know. Will do. Dave -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>