Re: [Crash-utility] [PATCH v2] files: support dump file pages from its address space

> I fixed line up problem in v3 patch, please check v3 patch in my another mail. > The major problem here is ADDR-SPACE and PAGE-COUNT width is greater than long size on 32 bit kernel. OK, thanks. But as far as the output display goes, I don't particularly like the naming of the "PAGE-CNT" column header. I'd prefer that it be changed to reflect the "address_space.nrpages" member that it comes from. I also think that the page count should be right-justified. So with this additional patch: --- filesys.c_oliver 2015-06-25 15:30:44.549942532 -0400 +++ filesys.c 2015-06-25 15:28:17.157947564 -0400 @@ -2370,13 +2370,12 @@ fill_task_struct(task); if (flags & PRINT_PAGES) { - sprintf(files_header, " FD%s%s%s%s%s%s%sTYPE%sPATH\n", + sprintf(files_header, " FD%s%s%s%s%sNRPAGES%sTYPE%sPATH\n", space(MINSPACE), mkstring(buf1, VADDR_PRLEN, CENTER|LJUST, "INODE"), space(MINSPACE), mkstring(buf2, VADDR_PRLEN, CENTER|LJUST, "MAPPING"), space(MINSPACE), - mkstring(buf3, LONG_PRLEN, CENTER|LJUST, "PAGE-CNT"), space(MINSPACE), space(MINSPACE)); } else { @@ -2935,8 +2934,8 @@ CENTER|RJUST|LONG_HEX, MKSTR(i_mapping)), space(MINSPACE), - mkstring(buf3, LONG_PRLEN, - CENTER|RJUST|LONG_DEC, + mkstring(buf3, strlen("NRPAGES"), + RJUST|LONG_DEC, MKSTR(count)), space(MINSPACE), type,

>> And secondly, taking the address_space e6c6a754 from the task above, >> again, shouldn't the page count above be reflected in the number of >> shown by the address_space tree dump, where the page dump seems to >> be missing about 20000 pages?: >> >> crash> files -m e6c6a754 | wc -l >> 128825 >> crash> > > I can't reproduce this issue on my 32bit kernel. > > Could you verify whether you can get the same number of pages by tree command? > > First step, get the page_tree address, > > address_space.page_tree e6c6a754 > > Second step, using tree command dump pages, > > tree -t radix -N <page_tree address> As it turns out, that dumpfile was created with the "snap.so" extension module, which creates a vmcore while running on a live system. And since the kernel is running while the dumpfile is being created, you may see any number of odd outputs. Running the "tree" command above fails with a duplicate list entry failure, so the "files -a" command should also fail prematurely. So it's not a problem.

>> >> For that matter, displaying the address_space address is redundant >> since (1) it has to be entered as the command argument, and (2) it gets >> shown in every page line "MAPPING". On the other hand, perhaps the inode >> that contains the address_space structure would be helpful, say, like >> this: > > In my v3 patch, I files -a accept inode as parameter, instead of address space address. OK, although I suggested "-a" because it was taking an "address_space" address as an argument. So perhaps it should be "-i <inode-address>"?

> The benefit of this change is, files -a is more separate with files -m. > > We decoupled two commands here. The first line of the page dump is kind of unusual: crash> files -a ffff8801085680b0 Address space ffff8801085681f0, 35002 pages PAGE PHYSICAL MAPPING INDEX CNT FLAGS ffffea00072ca3c0 1cb28f000 ffff8801085681f0 0 1 5ff0000002006c referenced,uptodate,lru,active,mappedtodisk ffffea0000c1f340 307cd000 ffff8801085681f0 200 1 3ff0000002006c referenced,uptodate,lru,active,mappedtodisk ffffea00030dea40 c37a9000 ffff8801085681f0 201 1 3ff0000002006c referenced,uptodate,lru,active,mappedtodisk ... Can you make it show INODE, ADDRESS_SPACE, and NRPAGES values (in that order), similar to how I suggested before? > But how about using -p instead of -a for page dump? Yes, sure -- either -i or -p makes sense.

So, aside from the patch I added above, the addition of the INODE, ADDRESS_SPACE and NRPAGES display to the top of the "files -i|p" command, and the help page additions, this is looking pretty good.