On Mon, 2009-09-21 at 15:40 +0200, Geert Uytterhoeven wrote: > > With 32-bit userland, this boils down to: > > | mmap addr 0x7fff0000 size 0x7fff0000 > | mmap returned 0x7fff0000 > > i.e. mmap() succeeds, but (1) the test expects it to fail, so the test returns > TFAIL, but (2) ltp-pan still reports that the tests passed?
What is the output of /proc/<pid>/maps after that mmap ? With a 64-bit kernel, 32-bit userspace has access to the entire 4G address space, so mapping 2G-64k at the 2G-64k point can work, provided you aren't overlapping an existing mapping such as the stack. > In addition, sometimes mmapstress03 fails due to SEGV. I created a small test > program that just does the above mmap(), and depending on the distro and what > else I print later it crashes with a SEGV, too. Probably this happens because > the mmap() did succeed, and corrupted some existing mappings, cfr. the notes > for MAP_FIXED: That's possible. > MAP_FIXED > Don’t interpret addr as a hint: place the mapping at exactly > that address. addr must be a multiple of the page size. If the > memory region specified by addr and len overlaps pages of any > existing mapping(s), then the overlapped part of the existing > mapping(s) will be discarded. If the specified address cannot > be used, mmap() will fail. Because requiring a fixed address > for a mapping is less portable, the use of this option is dis‐ > couraged. Yeah, I suppose the test might be wiping out its own stack for example IE. I think that test is just bogus :-) > JFYI, with 64-bit userland, this boils down to: > > | mmap addr 0x7fffffffffff0000 size 0x7fffffffffff0000 > | mmap returned 0xffffffffffffffff > > i.e. mmap() fails as expected, and the test succeeds. Right because on 64-bit userspace, you only are allowed something like 16T of address space. > Does all of this sound OK? > Thanks for your comments! Yes, I think so far, it's just bogus tests :-) Cheers, Ben. > With kind regards, > > Geert Uytterhoeven > Software Architect > Techsoft Centre > > Technology and Software Centre Europe > The Corporate Village · Da Vincilaan 7-D1 · B-1935 Zaventem · Belgium > > Phone: +32 (0)2 700 8453 > Fax: +32 (0)2 700 8622 > E-mail: geert.uytterhoe...@sonycom.com > Internet: http://www.sony-europe.com/ > > A division of Sony Europe (Belgium) N.V. > VAT BE 0413.825.160 · RPR Brussels > Fortis · BIC GEBABEBB · IBAN BE41293037680010 > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
