Re: [HACKERS] ReadBuffer(P_NEW) versus valid buffers
On Sun, Sep 24, 2006 at 12:26:55AM -0400, Alvaro Herrera wrote: Joshua D. Drake wrote: Tom Lane wrote: I asked around inside Red Hat but haven't gotten any responses yet ... seeing that it's a rather old Suse kernel, I can understand that RH's kernel hackers might not be too excited about investigating. (Alan Cox, for one, has got other things to worry about this weekend: http://zeniv.linux.org.uk/%7etelsa/boom/ Uhmm... doh? Telsa got fired for buying IBM? You should be fired for that pun. :P -- Jim Nasby[EMAIL PROTECTED] EnterpriseDB http://enterprisedb.com 512.569.9461 (cell) ---(end of broadcast)--- TIP 4: Have you searched our list archives? http://archives.postgresql.org
Re: [HACKERS] ReadBuffer(P_NEW) versus valid buffers
Tom Lane wrote: So ReadBuffer without hesitation zeroes out the page of data we just filled, and returns it for re-filling. There went some tuples :-( Although this is clearly Not Our Bug, it's annoying that ReadBuffer falls into the trap so easily instead of complaining. I'm still disinclined to try to change the behavior of mdread(), but what I am considering doing is adding a check here to error out if not PageIsNew. AFAICS, if we do find a buffer for a page supposedly past EOF, it should be zero-filled because that's what mdread returns in this case. So this change would prevent Dan's silent-overwrite scenario without changing the behavior for any legitimate case. Thoughts, problems, better ideas? The check looks good - are we chasing up the Linux kernel (or Suse) guys to get the bug investigated? Cheers Mark ---(end of broadcast)--- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
Re: [HACKERS] ReadBuffer(P_NEW) versus valid buffers
Mark Kirkwood [EMAIL PROTECTED] writes: The check looks good - are we chasing up the Linux kernel (or Suse) guys to get the bug investigated? I asked around inside Red Hat but haven't gotten any responses yet ... seeing that it's a rather old Suse kernel, I can understand that RH's kernel hackers might not be too excited about investigating. (Alan Cox, for one, has got other things to worry about this weekend: http://zeniv.linux.org.uk/%7etelsa/boom/ I believe Dan's busy updating his kernel --- if a current Suse kernel still shows the problem then he should definitely file a bug with them. regards, tom lane ---(end of broadcast)--- TIP 2: Don't 'kill -9' the postmaster
Re: [HACKERS] ReadBuffer(P_NEW) versus valid buffers
Tom Lane wrote: Mark Kirkwood [EMAIL PROTECTED] writes: The check looks good - are we chasing up the Linux kernel (or Suse) guys to get the bug investigated? I asked around inside Red Hat but haven't gotten any responses yet ... seeing that it's a rather old Suse kernel, I can understand that RH's kernel hackers might not be too excited about investigating. (Alan Cox, for one, has got other things to worry about this weekend: http://zeniv.linux.org.uk/%7etelsa/boom/ Uhmm... doh? Joshua D. Drake I believe Dan's busy updating his kernel --- if a current Suse kernel still shows the problem then he should definitely file a bug with them. regards, tom lane ---(end of broadcast)--- TIP 2: Don't 'kill -9' the postmaster ---(end of broadcast)--- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
Re: [HACKERS] ReadBuffer(P_NEW) versus valid buffers
Joshua D. Drake wrote: Tom Lane wrote: I asked around inside Red Hat but haven't gotten any responses yet ... seeing that it's a rather old Suse kernel, I can understand that RH's kernel hackers might not be too excited about investigating. (Alan Cox, for one, has got other things to worry about this weekend: http://zeniv.linux.org.uk/%7etelsa/boom/ Uhmm... doh? Telsa got fired for buying IBM? -- Alvaro Herrerahttp://www.CommandPrompt.com/ The PostgreSQL Company - Command Prompt, Inc. ---(end of broadcast)--- TIP 5: don't forget to increase your free space map settings
