The patch titled
Subject: mm/page_alloc.c: fix uninitialized memmaps on a partially populated last section
has been added to the -mm tree. Its filename is
mm-fix-uninitialized-memmaps-on-a-partially-populated-last-section.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-fix-uninitialized-memmaps-on-a-…
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-fix-uninitialized-memmaps-on-a-…
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: David Hildenbrand <david(a)redhat.com>
Subject: mm/page_alloc.c: fix uninitialized memmaps on a partially populated last section
If max_pfn is not aligned to a section boundary, we can easily run into
BUGs. This can e.g., be triggered on x86-64 under QEMU by specifying a
memory size that is not a multiple of 128MB (e.g., 4097MB, but also
4160MB). I was told that on real HW, we can easily have this scenario
(esp., one of the main reasons sub-section hotadd of devmem was added).
The issue is, that we have a valid memmap (pfn_valid()) for the whole
section, and the whole section will be marked "online".
pfn_to_online_page() will succeed, but the memmap contains garbage.
E.g., doing a "./page-types -r -a 0x144001" when QEMU was started with "-m
4160M" - (see tools/vm/page-types.c):
[ 200.476376] BUG: unable to handle page fault for address: fffffffffffffffe
[ 200.477500] #PF: supervisor read access in kernel mode
[ 200.478334] #PF: error_code(0x0000) - not-present page
[ 200.479076] PGD 59614067 P4D 59614067 PUD 59616067 PMD 0
[ 200.479557] Oops: 0000 [#4] SMP NOPTI
[ 200.479875] CPU: 0 PID: 603 Comm: page-types Tainted: G D W 5.5.0-rc1-next-20191209 #93
[ 200.480646] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu4
[ 200.481648] RIP: 0010:stable_page_flags+0x4d/0x410
[ 200.482061] Code: f3 ff 41 89 c0 48 b8 00 00 00 00 01 00 00 00 45 84 c0 0f 85 cd 02 00 00 48 8b 53 08 48 8b 2b 48f
[ 200.483644] RSP: 0018:ffffb139401cbe60 EFLAGS: 00010202
[ 200.484091] RAX: fffffffffffffffe RBX: fffffbeec5100040 RCX: 0000000000000000
[ 200.484697] RDX: 0000000000000001 RSI: ffffffff9535c7cd RDI: 0000000000000246
[ 200.485313] RBP: ffffffffffffffff R08: 0000000000000000 R09: 0000000000000000
[ 200.485917] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000144001
[ 200.486523] R13: 00007ffd6ba55f48 R14: 00007ffd6ba55f40 R15: ffffb139401cbf08
[ 200.487130] FS: 00007f68df717580(0000) GS:ffff9ec77fa00000(0000) knlGS:0000000000000000
[ 200.487804] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 200.488295] CR2: fffffffffffffffe CR3: 0000000135d48000 CR4: 00000000000006f0
[ 200.488897] Call Trace:
[ 200.489115] kpageflags_read+0xe9/0x140
[ 200.489447] proc_reg_read+0x3c/0x60
[ 200.489755] vfs_read+0xc2/0x170
[ 200.490037] ksys_pread64+0x65/0xa0
[ 200.490352] do_syscall_64+0x5c/0xa0
[ 200.490665] entry_SYSCALL_64_after_hwframe+0x49/0xbe
But it can be triggered much easier via "cat /proc/kpageflags > /dev/null"
after cold/hot plugging a DIMM to such a system:
[root@localhost ~]# cat /proc/kpageflags > /dev/null
[ 111.517275] BUG: unable to handle page fault for address: fffffffffffffffe
[ 111.517907] #PF: supervisor read access in kernel mode
[ 111.518333] #PF: error_code(0x0000) - not-present page
[ 111.518771] PGD a240e067 P4D a240e067 PUD a2410067 PMD 0
This patch fixes that by at least zero-ing out that memmap (so e.g.,
page_to_pfn() will not crash). Commit 907ec5fca3dc ("mm: zero remaining
unavailable struct pages") tried to fix a similar issue, but forgot to
consider this special case.
After this patch, there are still problems to solve. E.g., not all of
these pages falling into a memory hole will actually get initialized later
and set PageReserved - they are only zeroed out - but at least the
immediate crashes are gone. A follow-up patch will take care of this.
Link: http://lkml.kernel.org/r/20191211163201.17179-2-david@redhat.com
Fixes: f7f99100d8d9 ("mm: stop zeroing memory during allocation in vmemmap")
Signed-off-by: David Hildenbrand <david(a)redhat.com>
Tested-by: Daniel Jordan <daniel.m.jordan(a)oracle.com>
Cc: Naoya Horiguchi <n-horiguchi(a)ah.jp.nec.com>
Cc: Pavel Tatashin <pasha.tatashin(a)oracle.com>
Cc: Andrew Morton <akpm(a)linux-foundation.org>
Cc: Steven Sistare <steven.sistare(a)oracle.com>
Cc: Michal Hocko <mhocko(a)suse.com>
Cc: Daniel Jordan <daniel.m.jordan(a)oracle.com>
Cc: Bob Picco <bob.picco(a)oracle.com>
Cc: Oscar Salvador <osalvador(a)suse.de>
Cc: Alexey Dobriyan <adobriyan(a)gmail.com>
Cc: Dan Williams <dan.j.williams(a)intel.com>
Cc: Michal Hocko <mhocko(a)kernel.org>
Cc: Stephen Rothwell <sfr(a)canb.auug.org.au>
Cc: <stable(a)vger.kernel.org> [4.15+]
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/page_alloc.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
--- a/mm/page_alloc.c~mm-fix-uninitialized-memmaps-on-a-partially-populated-last-section
+++ a/mm/page_alloc.c
@@ -6932,7 +6932,8 @@ static u64 zero_pfn_range(unsigned long
* This function also addresses a similar issue where struct pages are left
* uninitialized because the physical address range is not covered by
* memblock.memory or memblock.reserved. That could happen when memblock
- * layout is manually configured via memmap=.
+ * layout is manually configured via memmap=, or when the highest physical
+ * address (max_pfn) does not end on a section boundary.
*/
void __init zero_resv_unavail(void)
{
@@ -6950,7 +6951,16 @@ void __init zero_resv_unavail(void)
pgcnt += zero_pfn_range(PFN_DOWN(next), PFN_UP(start));
next = end;
}
- pgcnt += zero_pfn_range(PFN_DOWN(next), max_pfn);
+
+ /*
+ * Early sections always have a fully populated memmap for the whole
+ * section - see pfn_valid(). If the last section has holes at the
+ * end and that section is marked "online", the memmap will be
+ * considered initialized. Make sure that memmap has a well defined
+ * state.
+ */
+ pgcnt += zero_pfn_range(PFN_DOWN(next),
+ round_up(max_pfn, PAGES_PER_SECTION));
/*
* Struct pages that do not have backing memory. This could be because
_
Patches currently in -mm which might be from david(a)redhat.com are
mm-fix-uninitialized-memmaps-on-a-partially-populated-last-section.patch
fs-proc-pagec-allow-inspection-of-last-section-and-fix-end-detection.patch
mm-initialize-memmap-of-unavailable-memory-directly.patch
mm-memory_hotplug-shrink-zones-when-offlining-memory.patch
mm-memory_hotplug-poison-memmap-in-remove_pfn_range_from_zone.patch
mm-memory_hotplug-we-always-have-a-zone-in-find_smallestbiggest_section_pfn.patch
mm-memory_hotplug-dont-check-for-all-holes-in-shrink_zone_span.patch
mm-memory_hotplug-drop-local-variables-in-shrink_zone_span.patch
mm-memory_hotplug-cleanup-__remove_pages.patch
The patch titled
Subject: mm/oom: fix pgtables units mismatch in Killed process message
has been added to the -mm tree. Its filename is
mm-oom-fix-pgtables-units-mismatch-in-killed-process-message.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-oom-fix-pgtables-units-mismatch…
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-oom-fix-pgtables-units-mismatch…
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Ilya Dryomov <idryomov(a)gmail.com>
Subject: mm/oom: fix pgtables units mismatch in Killed process message
pr_err() expects kB, but mm_pgtables_bytes() returns the number of bytes.
As everything else is printed in kB, I chose to fix the value rather than
the string.
Before:
[ pid ] uid tgid total_vm rss pgtables_bytes swapents oom_score_adj name
...
[ 1878] 1000 1878 217253 151144 1269760 0 0 python
...
Out of memory: Killed process 1878 (python) total-vm:869012kB, anon-rss:604572kB, file-rss:4kB, shmem-rss:0kB, UID:1000 pgtables:1269760kB oom_score_adj:0
After:
[ pid ] uid tgid total_vm rss pgtables_bytes swapents oom_score_adj name
...
[ 1436] 1000 1436 217253 151890 1294336 0 0 python
...
Out of memory: Killed process 1436 (python) total-vm:869012kB, anon-rss:607516kB, file-rss:44kB, shmem-rss:0kB, UID:1000 pgtables:1264kB oom_score_adj:0
Link: http://lkml.kernel.org/r/20191211202830.1600-1-idryomov@gmail.com
Fixes: 70cb6d267790 ("mm/oom: add oom_score_adj and pgtables to Killed process message")
Signed-off-by: Ilya Dryomov <idryomov(a)gmail.com>
Reviewed-by: Andrew Morton <akpm(a)linux-foundation.org>
Cc: Edward Chron <echron(a)arista.com>
Cc: Michal Hocko <mhocko(a)suse.com>
Cc: David Rientjes <rientjes(a)google.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
mm/oom_kill.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/oom_kill.c~mm-oom-fix-pgtables-units-mismatch-in-killed-process-message
+++ a/mm/oom_kill.c
@@ -890,7 +890,7 @@ static void __oom_kill_process(struct ta
K(get_mm_counter(mm, MM_FILEPAGES)),
K(get_mm_counter(mm, MM_SHMEMPAGES)),
from_kuid(&init_user_ns, task_uid(victim)),
- mm_pgtables_bytes(mm), victim->signal->oom_score_adj);
+ mm_pgtables_bytes(mm) >> 10, victim->signal->oom_score_adj);
task_unlock(victim);
/*
_
Patches currently in -mm which might be from idryomov(a)gmail.com are
mm-oom-fix-pgtables-units-mismatch-in-killed-process-message.patch
These were added to blkdev_ioctl() in linux-5.5 but not
blkdev_compat_ioctl, so add them now.
Cc: <stable(a)vger.kernel.org> # v4.4+
Fixes: bbd3e064362e ("block: add an API for Persistent Reservations")
Signed-off-by: Arnd Bergmann <arnd(a)arndb.de>
---
block/compat_ioctl.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/block/compat_ioctl.c b/block/compat_ioctl.c
index 5b13e344229c..f16ae92065d7 100644
--- a/block/compat_ioctl.c
+++ b/block/compat_ioctl.c
@@ -408,6 +408,14 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
case BLKTRACETEARDOWN: /* compatible */
ret = blk_trace_ioctl(bdev, cmd, compat_ptr(arg));
return ret;
+ case IOC_PR_REGISTER:
+ case IOC_PR_RESERVE:
+ case IOC_PR_RELEASE:
+ case IOC_PR_PREEMPT:
+ case IOC_PR_PREEMPT_ABORT:
+ case IOC_PR_CLEAR:
+ return blkdev_ioctl(bdev, mode, cmd,
+ (unsigned long)compat_ptr(arg));
default:
if (disk->fops->compat_ioctl)
ret = disk->fops->compat_ioctl(bdev, mode, cmd, arg);
--
2.20.0