The patch titled problems with cat /proc/kpageflags has been added to the -mm tree. Its filename is maps4-add-proc-kpageflags-interface-fix-2.patch *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: problems with cat /proc/kpageflags From: Matt Mackall <mpm@xxxxxxxxxxx> On Thu, Dec 20, 2007 at 04:17:26PM -0800, David Miller wrote: > From: Mariusz Kozlowski <m.kozlowski@xxxxxxxxxx> > Date: Thu, 20 Dec 2007 20:47:55 +0100 > > > [ 145.128915] TSTATE: 0000004411009603 TPC: 00000000005119ac TNPC: 00000000005119b0 Y: 00000000 Not tainted > > [ 145.128940] TPC: <kpagecount_read+0x94/0xe0> > > My suspicion at this point is that with certain RAM layouts, simply > iterating over PFN's is simply not working out. That was my original suspicion, which is why I asked Mariusz to effectively comment out the actual PFN lookup up-thread. I didn't send him a patch to do that, so I guess my instructions on how to hack it may have been misunderstood. > pfn_to_page() seems to be doing no range checking, and with sparsemem > vmemmap, which sparc64 always uses, this can be problematic. > > It just blindly goes "vmemmap + pfn" which is asking for trouble, in > particular when the physical RAM layout really is sparse. > > Maybe it's enough to add a pfn_valid() check here? If pfn_valid() > means there is a vmemmap translation setup for that page struct too, > it would work. Here's a test patch: Cc: Mariusz Kozlowski <m.kozlowski@xxxxxxxxxx> Cc: David Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/proc/proc_misc.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff -puN fs/proc/proc_misc.c~maps4-add-proc-kpageflags-interface-fix-2 fs/proc/proc_misc.c --- a/fs/proc/proc_misc.c~maps4-add-proc-kpageflags-interface-fix-2 +++ a/fs/proc/proc_misc.c @@ -699,7 +699,10 @@ static ssize_t kpagecount_read(struct fi return -EIO; while (count > 0) { - ppage = pfn_to_page(pfn++); + ppage = 0; + if (pfn_valid(pfn)) + ppage = pfn_to_page(pfn); + pfn++; if (!ppage) pcount = 0; else @@ -762,7 +765,10 @@ static ssize_t kpageflags_read(struct fi return -EIO; while (count > 0) { - ppage = pfn_to_page(pfn++); + ppage = 0; + if (pfn_valid(pfn)) + ppage = pfn_to_page(pfn); + pfn++; if (!ppage) kflags = 0; else _ Patches currently in -mm which might be from mpm@xxxxxxxxxxx are maps4-add-proportional-set-size-accounting-in-smaps.patch maps4-rework-task_size-macros.patch maps4-rework-task_size-macros-mips-fix.patch maps4-move-is_swap_pte.patch maps4-introduce-a-generic-page-walker.patch maps4-use-pagewalker-in-clear_refs-and-smaps.patch maps4-simplify-interdependence-of-maps-and-smaps.patch maps4-move-clear_refs-code-to-task_mmuc.patch maps4-regroup-task_mmu-by-interface.patch maps4-add-proc-pid-pagemap-interface.patch maps4-add-proc-kpagecount-interface.patch maps4-add-proc-kpagecount-interface-fix.patch maps4-add-proc-kpageflags-interface.patch maps4-add-proc-kpageflags-interface-fix.patch maps4-add-proc-kpageflags-interface-fix-2.patch maps4-make-page-monitoring-proc-file-optional.patch maps4-make-page-monitoring-proc-file-optional-fix.patch remove-unused-code-from-mm-tiny-shmemc.patch drivers-char-randomcwrite_pool-cond_resched-needed.patch printk_ratelimit-functions-should-use-config_printk.patch - To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html