Re: Setting bs could lead to some double free or segfault

From: Erwan Velu <>
Date: Fri, 20 Jul 2007 12:18:00 +0200

Erwan Velu wrote:
> Note, that setting bs=4k __and__ direct=1 make things work perfectly
> (but in that test I would like not beeing O_DIRECT ;))
> So its sounds that a 4k bs with direct=0 generates the troubles.
I found other value that could generates troubles (even if some are
stupid I admit it but it might could help to find some limits :b ) :
I was just checking this values to see what happens when a typo occurs
whereas the 4k is a real case ;)

bs size result

0k -> fio: pid=19381, got signal=8 + fio[19381] trap divide error
rip:40dd89 rsp:7fffffc5d4e0 error:0
-1k -> fio: pid=19396, err=12/file:memory.c:160, func=iomem allocation,
error=Cannot allocate memory

4194000k -> job1: (g=0): rw=read,
bs=4194000K-4194000K/4194000K-4194000K, ioengine=sync, iodepth=1
4195000k -> job1: (g=0): rw=read, bs=696K-696K/696K-696K, ioengine=sync,

As you see after 4194000k, fio reports strange sizes.

Received on Fri Jul 20 2007 - 12:18:00 CEST

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