> On Mon, Apr 19, 2010 at 6:26 PM, John David Anglin > <dave@xxxxxxxxxxxxxxxxxx> wrote: > > Hi Helge, > > > > On Tue, 13 Apr 2010, Helge Deller wrote: > > > >> Still crashes. > > > > Can you you try the patch below? =C2=A0The change to cacheflush.h is the = > same > > as before. > > For the records, while setting up the wiki's TestCases page, it > noticed that the initial large patch that you sent (see > https://patchwork.kernel.org/patch/91525/ ) contained bits that > weren't part of the split chunks you sent afterwards. > > This patch (pte.d.2) seems to update some of those chunks and also > contains bits that weren't either part of them. The split chunks were mainly cleanups. As far as I know, they are obvious and provide no significant change in functionality. I didn't intentionally change any of the split hunks in patch4 (pte.d.2) although this patch does touch some of the same files. Possibly, the LWS fixes should be split into two (obvious and UP locking). Both the original patch and pte.d.2 were experimental. Since I sent it, I continued to experiment and reached a change that appears to fix the minifail bug in a somewhat different manner than proposed by James. However, I'm still seeing some issues that appear to be PTE related (segmentation faults in sh mainly). At this point, I don't know why I still see problems. I have one idea left to try. I also would like to implement copy_user_page with equivalent aliasing. My first attempt didn't work. I just enabled code in pacache.S. I have more or less reached the conclusion that our PTE/TLB management is quite broken on SMP. I tried James' patch but had trouble with segmention faults on my rp3440 and a GCC build died early in stage 1 (make -j8 bootstrap). I need to try it with a clean build. I may be wrong but I think a flush in kmap(_atomic) won't work on SMP because another user may just redirty the page when it is shared. > That being said so that we do not loose track of potentially useful > code. Though maybe kyle has all of this sorted out already and I'm > just unable to figure it out myself ;-) I don't think there's a clear path. I've come to realize that I don't understand what's required of the higher level code. The documentation doesn't help much. Looking at other archs provides some clues. I've looked at ia64 a bit (see for example TLB shootout support and retry in TLB miss handler). Regarding the wiki, it's a useful summary. However, #561203 (minifail bug) is not a "Futex wait failure". We may have futex bugs, but I'm not aware of a testcase. The minifail bug is a "Threads and fork" problem arising from cache corruption. Mainly, copy_user_page is broken when copying memory shared by more than one process. There are also issues in PTE/TLB management on SMP systems. Probably, the vfork/execve bug is caused by the same problem. Dave -- J. David Anglin dave.anglin@xxxxxxxxxxxxxx National Research Council of Canada (613) 990-0752 (FAX: 952-6602) -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
