Messages in this thread | | | Subject | Re: Bisected 3.9 regression: Corrupted low memory (x86, mm: Move reserving low memory later in initialization) | From | "H. Peter Anvin" <> | Date | Wed, 21 May 2014 11:03:59 -0700 |
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Yes, I'm sure. The old memory reservation code kept the checker from working.
On May 21, 2014 10:58:39 AM PDT, "Rafał Miłecki" <zajec5@gmail.com> wrote: >On 21 May 2014 19:34, H. Peter Anvin <hpa@zytor.com> wrote: >> On 05/21/2014 06:31 AM, Rafał Miłecki wrote: >>> On 16 May 2014 07:29, Rafał Miłecki <zajec5@gmail.com> wrote: >>>> Sorry for the late report, this bug appears on my old notebook I >don't >>>> commonly use. Anyway, I've noticed following problem when using >>>> 3.15-rc1: >>>> >>>> Corrupted low memory at ffff88000000be98 (be98 phys) = >b02a000400000000 >>> >>> Ping? >>> >> >> It's not a regression, but rather a progression: the checker now does >> what it claims to do, which is to check for low memory corruption. >> >> However, the checker is also rather useless as anything other than a >> diagnostic tool. It tells you that your BIOS is corrupting memory, >and >> the solution to that is to reserve the memory, which we already do. >> >> All the checker tells us is that on your system, yes, we really do >need >> to reserve the memory. > >What about making checker a bit more user friendly? > >First of all, I got many repeated messages like: >Corrupted low memory at (...) >In the first e-mail you can see ~10 of them and I really got more. > >Secondly, if this is just a confirmation that low memory reservation >was indeed needed, what about making it debugging only? Right now it >sounds like an error for end-users. What about making it something >like >Low memory reservation prevented corruption at (...) > >The last question, just for sure... are you convinced what I'm seeing >is not any kind of error? After all, it started appearing after commit >that moves memory reservation. It's not a commit that enabled the >checker or something like that. >What it seems to be for someone not experienced is a bit opposite. It >looks that after commit in question, kernel reserves low memory too >late and BIOS already corrupts some data placed in it. >However I'm not on expert, so I'll just listen to your opinion. I >simply wanted to ask, just to be sure everything is alright.
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