Hi Roland, > > So it appears to me that different code is activated for regular users > > and root.
In addition to the filesystem device difference (discussed below), the other highly relevant difference is that processes run as root are terminated by the OOM killer with a slower priority. This is unlikely to be the underlying issue of course, but it will introduce uncertainty to any experiment or testcase. > I think I've found the cause for the different code paths. > The squashfs image contains devices, which can only be extracted as root. Ah, bravo — well discovered! Alas, I'm afraid I should have been able to help you come to this earlier, for I clearly encountered precisely this issue before and had completely forgotten about it: https://salsa.debian.org/reproducible-builds/diffoscope/commit/95dbe95a471e127798614727deea637186c1364f https://salsa.debian.org/reproducible-builds/diffoscope/-/issues/63 (I will be the first to admit that I did not really resolve the underlying problem, merely prevented it from coming up in the testsuite.) One question though — why would the character devices existing or not be relevant to it OOMing? Or rather, why aren't they simply compared in the normal way? Sure, if character devices exist they will take extra time and resources to be compared, but surely your ISO does not contain so many character devices that it adds a significant burden to the comparison process? > With squashfuse (mounting the image in userspace) to replace the > unpacking to disc with unsquashfs, this issue might be avoided. Oh that's an interesting idea. However, let's keep it in the back pocket for now — filesystem mounting (particularly of the FUSE variety) would not be a trivial addition to diffoscope, so we should be sure the effort and complexity is justified first. Let's take stock. What do we want this diffoscope invocation on Jenkins to actually do? In the first instance, we obviously don't want it to OOM. But do we want it to extract these character devices or not? And if we want or can skip over them, what should we do in that situation? And is that going to be helpful at all in this OOM situation anyway? (A side question: can you confirm whether diffoscope is running as root or not in your particular Jenkins test? I don't want to misinterpret the logs.) Best wishes, -- o ⬋ ⬊ Chris Lamb o o reproducible-builds.org 💠 ⬊ ⬋ o _______________________________________________ Reproducible-builds mailing list Reproducible-builds@alioth-lists.debian.net https://alioth-lists.debian.net/cgi-bin/mailman/listinfo/reproducible-builds
