Messages in this thread | | | Date | Wed, 25 Apr 2001 18:10:16 -0700 | From | Andrew Morton <> | Subject | Re: Weird problem with 2.4.4-pre6 |
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Tobias Ringstrom wrote: > > Yesterday, I was running tcpdump, paging the output with less. All of a > sudden, less started to dump core (SIGSEGV). I could not even start less > by itself: > > > less > > without it getting a SIGSEGV, and in fact no user could run less without > getting a SIGSEGV, but it did work perfectly a few minutes earlier. This > morning, I tried to run less again, and now it was working! No core > dumps! > > How can this happen? Something overwriting the page/buffer cache?
Yes. Something scribbled on the pagecache, most likely.
If this happens, take a copy of the offending binary and all its shared libraries - simply copy them into a temp directory. The corrupted version will be written to disk, from the pagecache. Make sure you keep a copy of the offending vmlinux as well for looking things up in.
Then reboot and start diffing things; the differences can provide clues. If the diffs show single-bit errors then it's a RAM problem. If the diffs look like pointers into kernel space then look 'em up in vmlinux and shout loudly. etc.
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