The patch titled
problems with cat /proc/kpageflags
has been removed from the -mm tree. Its filename was
maps4-add-proc-kpageflags-interface-fix-2.patch
This patch was dropped because it was folded into maps4-add-proc-kpageflags-interface.patch
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
origin.patch
maps4-add-proportional-set-size-accounting-in-smaps.patch
maps4-rework-task_size-macros.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-kpageflags-interface.patch
maps4-add-proc-kpageflags-interface-fix-2.patch
maps4-add-proc-kpageflags-interface-fix-2-fix.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
slob-fix-free-block-merging-at-head-of-subpage.patch
slob-reduce-external-fragmentation-by-using-three-free-lists.patch
slob-correct-kconfig-description.patch
drivers-char-randomcwrite_pool-cond_resched-needed.patch
random-clean-up-checkpatch-complaints.patch
random-consolidate-wakeup-logic.patch
random-use-unlocked_ioctl.patch
random-reuse-rand_initialize.patch
random-improve-variable-naming-clear-extract-buffer.patch
random-make-backtracking-attacks-harder.patch
random-remove-cacheline-alignment-for-locks.patch
random-eliminate-redundant-new_rotate-variable.patch
random-remove-some-prefetch-logic.patch
random-simplify-add_ptr-logic.patch
random-make-mixing-interface-byte-oriented.patch
random-simplify-and-rename-credit_entropy_store.patch
random-add-async-notification-support-to-dev-random.patch
-
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