Hi Fan, please give your comments on this issue.
It is glibc and kernel issue discussions. http://bugs.gentoo.org/197191 Is this info is up to the date? http://www.opengroup.org/onlinepubs/009695399/functions/mmap.html I did not find mmap (3) in kernel man pages. http://www.kernel.org/doc/man-pages/online/dir_section_3.html I am not sure about glibc mmap implementation. http://sources.redhat.com/cgi-bin/cvsweb.cgi/?cvsroot=glibc if you find any info. please share. Best regards, Naresh Kamboju On Fri, Aug 7, 2009 at 6:11 PM, Subrata Modak<[email protected]> wrote: > On Thu, 2009-08-06 at 21:39 +0530, naresh kamboju wrote: >> Hi, >> >> In addition to the below Link discussion >> >> Date: 16 Jul 2009 >> http://www.mail-archive.com/[email protected]/msg07506.html >> >> patch is not yet committed to LTP CVs. > > I am a bit perplexed by all these links. Can you please RESEND the > concerned patch with the required description. I would then check that > in. > > Regards-- > Subrata > >> >> as per test case Description >> >> /*****************************************************/ >> * Implementation performs mapping operations over whole pages. >> * Thus, while the argument len >> * need not meet a size or alignment constraint, >> * the implementation shall include, in any mapping >> * operation, any partial page specified by the range [pa,pa+len). >> * The system shall always zero-fill any partial page at the end of an >> object. >> * Further, the system shall never write out any modified portions of >> * the last page of an object which are beyond its end. >> * >> * Test step: >> * 1. Create a process, in this process: >> a. map a file with size of 1/2 * page_size, >> * set len = 1/2 * page_size >> * b. Read the partial page beyond the object size. >> * Make sure the partial page is zero-filled; >> * c. Modify a byte in the partial page, then un-map the and close the >> * file descriptor. >> * 2. Wait for the child proces to exit, then >> * Map the file again, >> * read the byte from the position modified at step 1-c and check. >> */ >> /****************************************************/ >> >> please note the below discussion >> >> http://bugs.gentoo.org/197191 >> >> Ref: >> http://www.opengroup.org/onlinepubs/009695399/functions/mmap.html >> >> fan he, >> >> please make sure who is going to do this is it coming from kernel or glibc? >> >> Best regards >> Naresh Kamboju >> >> >> >On Mon, 2009-07-20 at 00:46 -0700, Garrett Cooper wrote: >> > On Sun, Jul 19, 2009 at 10:54 PM, Michal >> > Simek<[email protected]> wrote: >> > > Hi, >> > >> On Sat, 2009-07-18 at 12:28 -0700, Garrett Cooper wrote: >> > >> >> > >>> On Thu, Jul 16, 2009 at 11:37 PM, hefan<[email protected]> wrote: >> > >>> >> > >>>> hi, >> > >>>> >> > >>>> *[Patch 1/1] Patch for fixing the failed testcase >> > >>>> openposix_mmap_11_4 >> > >>>> >> > >>>> -modified the file >> > >>>> *testcases/open_posix_testsuite/conformance/interfaces/mmap/11-4.c >> > > >> > > First of all - this is really small explanation why you are fixing this >> > > issue. After some month >> > > none will know why you did this change. >> > > >> > > >> > >>>> >> > >>>> Signed-off-by: fredrick he <[email protected]> >> > >>>> >> > >>>> --- >> > >>>> ltp.orig/testcases/open_posix_testsuite/conformance/interfaces/mmap/11-4.c >> > >>>> 2009-07-17 11:53:36.000000000 +0800 >> > >>>> +++ >> > >>>> ltp/testcases/open_posix_testsuite/conformance/interfaces/mmap/11-4.c >> > >>>> 2009-07-17 11:57:09.000000000 +0800 >> > >>>> @@ -130,7 +130,9 @@ int main() >> > >>>> flag = MAP_SHARED; >> > >>>> off = 0; >> > >>>> pa = mmap(addr, len, prot, flag, fd_2, off); >> > >>>> - pa_2 = mmap(addr, len, prot, flag, fd_2, off); >> > >>>> + addr = pa; >> > >>>> + memset(addr,0,len*2); >> > >>>> + pa_2 = mmap(addr, len, prot, flag|MAP_FIXED, fd_2, off); >> > >>>> if (pa_2 == MAP_FAILED) >> > >>>> { >> > >>>> printf("Test FAIL: " TNAME " Error at 2nd mmap(): %s\n", >> > >>>> >> > >>> Hi Fan, >> > >>> Some questions / observations: >> > >>> >> > >>> 1. Yes, the testcases does fail on my machine today. >> > >>> 2. Yes, doing what you say above does work (at least the testcase >> > >>> passes). >> > >>> 3. Are you positive that your set of steps above in fact don't >> > >>> invalidate the purpose of the testcase, by accident, in particular the >> > >>> memset call? I ask because of the following statement in the mmap >> > >>> manpage: >> > >>> >> > >>> If addr is NULL, then the kernel chooses the address at which to >> > >>> create >> > >>> the mapping; this is the most portable method of creating a >> > >>> new >> > >>> map- >> > >>> ping. If addr is not NULL, then the kernel takes it as a >> > >>> hint >> > >>> about >> > >>> where to place the mapping; on Linux, the mapping will be >> > >>> created >> > >>> at a >> > >>> nearby page boundary. The address of the new mapping is >> > >>> returned as >> > >>> the result of the call. >> > >>> >> > >>> What you're in effect doing is changing the 2nd mmap call from an >> > >>> arbitrary address to a set virtual address at 0x0. Is that indeed >> > >>> correct? >> > >>> >> > >> in this case, the situation is like this, we create a new file about 512 >> > >> bytes and mmap it into the mem, then we modify one byte besides the 512 >> > >> bytes address, and munmap it. and in the father process remmap it back >> > >> to check whether the one more byte is write back to the files. >> > >> > Ok. >> > >> > >> i have checked that when finished munmap and close the file in the child >> > >> process, the file didn't contain the 513th byte, the size of this file >> > >> is right 512 bytes.but in this case after the second mmap finished, the >> > >> 513th byte does appear again. it's a conflict. >> > >> >> > >> in my opinion this is because of the compiler or some optimizations. so >> > >> i think the memory should to be memset before mmap and it does work. >> > >> > No, according to the manpage it'll map to the boundary of the closest >> > page size, in my opinion what might be occurring is the system is >> > either overallocating or underallocating, depending on the system page >> > size and what's being passed in for a length. What the page size is, >> > I'd surely like to know... >> here in my environment the page size is 1024 got by using >> sysconf(_SC_PAGE_SIZE) in this testcase >> > >> > > If is the problem with compiler/optimization means that tests is ok - >> > > the problem is with your >> > > compiler not with code. >> > > This need more investigations to find out where the problem is. >> > >> > I wouldn't necessarily say that. Based on Frederick's explanation, it >> > sounds like someone fed in an inappropriate bound, or didn't NUL >> > terminate the boundary and just went off into uncharted territory >> > without first checking where they were `on the map'. >> > >> > Based on my experience and recollection, this is legitimate in C >> > behavior as long as you're within the applications memory limits -- >> > you've just entered the twilight zone between realities, where you're >> > beyond your address space, but not beyond the point of no return >> > (EACCES), where the kernel *should* terminate your userland app. >> >yeah, that's the keypoint. but it doesn't terminate our userland app. >> >> >i mean that here is a mistake on the way this testcase check the result. >> >ideally, the mmap should only use half a page and it has no >> >resposibility on the rest of the page, so we shouldn't judge the mmap by >> >the rest of the page which is none of business with mmap. >> >> >so if we suppose that the mmap does affect the rest of the page( is it >> >the purpose to design this testcase ? ), we should make sure that this >> >area has been clear before we mmap the file into this area. that's why i >> >use memset and flag MAP_FIXED. >> >> > >> > Whether or not that was the intention of the POSIX folks, is another >> > question indeed, as the documentation states (in the header of the .c >> > file): >> > >> > * Implementation performs mapping operations over whole pages. >> > * Thus, while the argument len >> > * need not meet a size or alignment constraint, >> > * the implementation shall include, in any mapping >> > * operation, any partial page specified by the range [pa,pa+len). >> > * The system shall always zero-fill any partial page at the end of an >> > object. >> > * Further, the system shall never write out any modified portions of >> > * the last page of an object which are beyond its end. >> > >> > So unless they're completely misinterpreting the meaning of mmap, it >> > sounds like there's a bug in a number of `POSIX-compliant' operating >> > systems that needs to be resolved (FreeBSD and Linux included). >> > >> > However, before jumping to conclusions, I think that it's prudent to >> > narrow down where and why this is occurring... >> > >> > >>> 4. Have you talked to the openposix test suite folks about this yet? >> > >>> >> > >> no,i have no idea on how to talk to the openposix and i do want to talk >> > >> to them :) can you give me some suggestions about this? thx~ >> > >> > The project administrators are available, as noted, here: >> > >> > https://sourceforge.net/project/memberlist.php?group_id=64592 >> > >> > Thanks, >> > -Garrett > > ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Ltp-list mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/ltp-list
