Getting -EBUSY from zs_page_migrate will make migration slow (retry) or
fail (zs_page_putback will schedule_work free_work, but it cannot ensure
the success).
I noticed this issue because my Kernel patched
(https://lkml.org/lkml/2014/5/28/113) that will remove retry in
__alloc_contig_migrate_range.
This retry will handle the -EBUSY because it will re-isolate the page
and re-call migrate_pages. Without it will make cma_alloc fail at once
with -EBUSY.
According to the review from Minchan Kim in
https://lkml.org/lkml/2014/5/28/113, I update the patch to skip
unnecessary loops but not return -EBUSY if zspage is not inuse.
Following is what I got with highalloc-performance in a vbox with 2 cpu
1G memory 512 zram as swap. And the swappiness is set to 100.
ori ne
orig new
Minor Faults 50805113 50830235
Major Faults 43918 56530
Swap Ins 42087 55680
Swap Outs 89718 104700
Allocation stalls 0 0
DMA allocs 57787 52364
DMA32 allocs 47964599 48043563
Normal allocs 0 0
Movable allocs 0 0
Direct pages scanned 45493 23167
Kswapd pages scanned 1565222 1725078
Kswapd pages reclaimed 1342222 1503037
Direct pages reclaimed 45615 25186
Kswapd efficiency 85% 87%
Kswapd velocity 1897.101 1949.042
Direct efficiency 100% 108%
Direct velocity 55.139 26.175
Percentage direct scans 2% 1%
Zone normal velocity 1952.240 1975.217
Zone dma32 velocity 0.000 0.000
Zone dma velocity 0.000 0.000
Page writes by reclaim 89764.000 105233.000
Page writes file 46 533
Page writes anon 89718 104700
Page reclaim immediate 21457 3699
Sector Reads 3259688 3441368
Sector Writes 3667252 3754836
Page rescued immediate 0 0
Slabs scanned 1042872 1160855
Direct inode steals 8042 10089
Kswapd inode steals 54295 29170
Kswapd skipped wait 0 0
THP fault alloc 175 154
THP collapse alloc 226 289
THP splits 0 0
THP fault fallback 11 14
THP collapse fail 3 2
Compaction stalls 536 646
Compaction success 322 358
Compaction failures 214 288
Page migrate success 119608 111063
Page migrate failure 2723 2593
Compaction pages isolated 250179 232652
Compaction migrate scanned 9131832 9942306
Compaction free scanned 2093272 2613998
Compaction cost 192 189
NUMA alloc hit 47124555 47193990
NUMA alloc miss 0 0
NUMA interleave hit 0 0
NUMA alloc local 47124555 47193990
NUMA base PTE updates 0 0
NUMA huge PMD updates 0 0
NUMA page range updates 0 0
NUMA hint faults 0 0
NUMA hint local faults 0 0
NUMA hint local percent 100 100
NUMA pages migrated 0 0
AutoNUMA cost 0% 0%
[akpm@linux-foundation.org: remove newline, per Minchan]
Link: http://lkml.kernel.org/r/1500889535-19648-1-git-send-email-zhuhui@xiaomi.com
Signed-off-by: Hui Zhu <zhuhui@xiaomi.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Nadav Amit report zap_page_range only specifies that the caller protect
the VMA list but does not specify whether it is held for read or write
with callers using either. madvise holds mmap_sem for read meaning that
a parallel zap operation can unmap PTEs which are then potentially
skipped by madvise which potentially returns with stale TLB entries
present. While the API could be extended, it would be a difficult API
to use. This patch causes zap_page_range() to always consider flushing
the full affected range. For small ranges or sparsely populated
mappings, this may result in one additional spurious TLB flush. For
larger ranges, it is possible that the TLB has already been flushed and
the overhead is negligible. Either way, this approach is safer overall
and avoids stale entries being present when madvise returns.
This can be illustrated with the following program provided by Nadav
Amit and slightly modified. With the patch applied, it has an exit code
of 0 indicating a stale TLB entry did not leak to userspace.
---8<---
volatile int sync_step = 0;
volatile char *p;
static inline unsigned long rdtsc()
{
unsigned long hi, lo;
__asm__ __volatile__ ("rdtsc" : "=a"(lo), "=d"(hi));
return lo | (hi << 32);
}
static inline void wait_rdtsc(unsigned long cycles)
{
unsigned long tsc = rdtsc();
while (rdtsc() - tsc < cycles);
}
void *big_madvise_thread(void *ign)
{
sync_step = 1;
while (sync_step != 2);
madvise((void*)p, PAGE_SIZE * N_PAGES, MADV_DONTNEED);
}
int main(void)
{
pthread_t aux_thread;
p = mmap(0, PAGE_SIZE * N_PAGES, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
memset((void*)p, 8, PAGE_SIZE * N_PAGES);
pthread_create(&aux_thread, NULL, big_madvise_thread, NULL);
while (sync_step != 1);
*p = 8; // Cache in TLB
sync_step = 2;
wait_rdtsc(100000);
madvise((void*)p, PAGE_SIZE, MADV_DONTNEED);
printf("data: %d (%s)\n", *p, (*p == 8 ? "stale, broken" : "cleared, fine"));
return *p == 8 ? -1 : 0;
}
---8<---
Link: http://lkml.kernel.org/r/20170725101230.5v7gvnjmcnkzzql3@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reported-by: Nadav Amit <nadav.amit@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When walking the page tables to resolve an address that points to
!p*d_present() entry, huge_pte_offset() returns inconsistent values
depending on the level of page table (PUD or PMD).
It returns NULL in the case of a PUD entry while in the case of a PMD
entry, it returns a pointer to the page table entry.
A similar inconsitency exists when handling swap entries - returns NULL
for a PUD entry while a pointer to the pte_t is retured for the PMD
entry.
Update huge_pte_offset() to make the behaviour consistent - return a
pointer to the pte_t for hugepage or swap entries. Only return NULL in
instances where we have a p*d_none() entry and the size parameter
doesn't match the hugepage size at this level of the page table.
Document the behaviour to clarify the expected behaviour of this
function. This is to set clear semantics for architecture specific
implementations of huge_pte_offset().
Discussions on the arm64 implementation of huge_pte_offset()
(http://www.spinics.net/lists/linux-mm/msg133699.html) showed that there
is benefit from returning a pte_t* in the case of p*d_none().
The fault handling code in hugetlb_fault() can handle p*d_none() entries
and saves an extra round trip to huge_pte_alloc(). Other callers of
huge_pte_offset() should be ok as well.
[punit.agrawal@arm.com: v2]
Link: http://lkml.kernel.org/r/20170725154114.24131-2-punit.agrawal@arm.com
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
These functions are the only bits of generic code that use
{pud,pmd}_pfn() without checking for CONFIG_TRANSPARENT_HUGEPAGE. This
works fine on x86, the only arch with devmap support, since the *_pfn()
functions are always defined there, but this isn't true for every
architecture.
Link: http://lkml.kernel.org/r/20170626063833.11094-1-oohall@gmail.com
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mremap will attempt to create a 'duplicate' mapping if old_size == 0 is
specified. In the case of private mappings, mremap will actually create
a fresh separate private mapping unrelated to the original. This does
not fit with the design semantics of mremap as the intention is to
create a new mapping based on the original.
Therefore, return EINVAL in the case where an attempt is made to
duplicate a private mapping. Also, print a warning message (once) if
such an attempt is made.
Link: http://lkml.kernel.org/r/cb9d9f6a-7095-582f-15a5-62643d65c736@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Aaron Lu <aaron.lu@intel.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
init_pages_in_zone() is run under zone->lock, which means a long lock
time and disabled interrupts on large machines. This is currently not
an issue since it runs early in boot, but a later patch will change
that.
However, like other pfn scanners, we don't actually need zone->lock even
when other cpus are running. The only potentially dangerous operation
here is reading bogus buddy page owner due to race, and we already know
how to handle that. The worst that can happen is that we skip some
early allocated pages, which should not affect the debugging power of
page_owner noticeably.
Link: http://lkml.kernel.org/r/20170720134029.25268-4-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Yang Shi <yang.shi@linaro.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: zhong jiang <zhongjiang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
page_ext_init() can take long on large machines, so add a cond_resched()
point after each section is processed. This will allow moving the init
to a later point at boot without triggering lockup reports.
Link: http://lkml.kernel.org/r/20170720134029.25268-3-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Yang Shi <yang.shi@linaro.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: zhong jiang <zhongjiang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In init_pages_in_zone() we currently use the generic set_page_owner()
function to initialize page_owner info for early allocated pages. This
means we needlessly do lookup_page_ext() twice for each page, and more
importantly save_stack(), which has to unwind the stack and find the
corresponding stack depot handle. Because the stack is always the same
for the initialization, unwind it once in init_pages_in_zone() and reuse
the handle. Also avoid the repeated lookup_page_ext().
This can significantly reduce boot times with page_owner=on on large
machines, especially for kernels built without frame pointer, where the
stack unwinding is noticeably slower.
[vbabka@suse.cz: don't duplicate code of __set_page_owner(), per Michal Hocko]
[akpm@linux-foundation.org: coding-style fixes]
[vbabka@suse.cz: create statically allocated fake stack trace for early allocated pages, per Michal]
Link: http://lkml.kernel.org/r/45813564-2342-fc8d-d31a-f4b68a724325@suse.cz
Link: http://lkml.kernel.org/r/20170720134029.25268-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Yang Shi <yang.shi@linaro.org>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: zhong jiang <zhongjiang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit f52407ce2d ("memory hotplug: alloc page from other node in
memory online") has introduced N_HIGH_MEMORY checks to only use NUMA
aware allocations when there is some memory present because the
respective node might not have any memory yet at the time and so it
could fail or even OOM.
Things have changed since then though. Zonelists are now always
initialized before we do any allocations even for hotplug (see
959ecc48fc ("mm/memory_hotplug.c: fix building of node hotplug
zonelist")).
Therefore these checks are not really needed. In fact caller of the
allocator should never care about whether the node is populated because
that might change at any time.
Link: http://lkml.kernel.org/r/20170721143915.14161-10-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
zonelists_mutex was introduced by commit 4eaf3f6439 ("mem-hotplug: fix
potential race while building zonelist for new populated zone") to
protect zonelist building from races. This is no longer needed though
because both memory online and offline are fully serialized. New users
have grown since then.
Notably setup_per_zone_wmarks wants to prevent from races between memory
hotplug, khugepaged setup and manual min_free_kbytes update via sysctl
(see cfd3da1e49 ("mm: Serialize access to min_free_kbytes"). Let's
add a private lock for that purpose. This will not prevent from seeing
halfway through memory hotplug operation but that shouldn't be a big
deal becuse memory hotplug will update watermarks explicitly so we will
eventually get a full picture. The lock just makes sure we won't race
when updating watermarks leading to weird results.
Also __build_all_zonelists manipulates global data so add a private lock
for it as well. This doesn't seem to be necessary today but it is more
robust to have a lock there.
While we are at it make sure we document that memory online/offline
depends on a full serialization either via mem_hotplug_begin() or
device_lock.
Link: http://lkml.kernel.org/r/20170721143915.14161-9-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Haicheng Li <haicheng.li@linux.intel.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
build_all_zonelists has been (ab)using stop_machine to make sure that
zonelists do not change while somebody is looking at them. This is is
just a gross hack because a) it complicates the context from which we
can call build_all_zonelists (see 3f906ba236 ("mm/memory-hotplug:
switch locking to a percpu rwsem")) and b) is is not really necessary
especially after "mm, page_alloc: simplify zonelist initialization" and
c) it doesn't really provide the protection it claims (see below).
Updates of the zonelists happen very seldom, basically only when a zone
becomes populated during memory online or when it loses all the memory
during offline. A racing iteration over zonelists could either miss a
zone or try to work on one zone twice. Both of these are something we
can live with occasionally because there will always be at least one
zone visible so we are not likely to fail allocation too easily for
example.
Please note that the original stop_machine approach doesn't really
provide a better exclusion because the iteration might be interrupted
half way (unless the whole iteration is preempt disabled which is not
the case in most cases) so the some zones could still be seen twice or a
zone missed.
I have run the pathological online/offline of the single memblock in the
movable zone while stressing the same small node with some memory
pressure.
Node 1, zone DMA
pages free 0
min 0
low 0
high 0
spanned 0
present 0
managed 0
protection: (0, 943, 943, 943)
Node 1, zone DMA32
pages free 227310
min 8294
low 10367
high 12440
spanned 262112
present 262112
managed 241436
protection: (0, 0, 0, 0)
Node 1, zone Normal
pages free 0
min 0
low 0
high 0
spanned 0
present 0
managed 0
protection: (0, 0, 0, 1024)
Node 1, zone Movable
pages free 32722
min 85
low 117
high 149
spanned 32768
present 32768
managed 32768
protection: (0, 0, 0, 0)
root@test1:/sys/devices/system/node/node1# while true
do
echo offline > memory34/state
echo online_movable > memory34/state
done
root@test1:/mnt/data/test/linux-3.7-rc5# numactl --preferred=1 make -j4
and it survived without any unexpected behavior. While this is not
really a great testing coverage it should exercise the allocation path
quite a lot.
Link: http://lkml.kernel.org/r/20170721143915.14161-8-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
build_zonelists gradually builds zonelists from the nearest to the most
distant node. As we do not know how many populated zones we will have
in each node we rely on the _zoneref to terminate initialized part of
the zonelist by a NULL zone. While this is functionally correct it is
quite suboptimal because we cannot allow updaters to race with zonelists
users because they could see an empty zonelist and fail the allocation
or hit the OOM killer in the worst case.
We can do much better, though. We can store the node ordering into an
already existing node_order array and then give this array to
build_zonelists_in_node_order and do the whole initialization at once.
zonelists consumers still might see halfway initialized state but that
should be much more tolerateable because the list will not be empty and
they would either see some zone twice or skip over some zone(s) in the
worst case which shouldn't lead to immediate failures.
While at it let's simplify build_zonelists_node which is rather
confusing now. It gets an index into the zoneref array and returns the
updated index for the next iteration. Let's rename the function to
build_zonerefs_node to better reflect its purpose and give it zoneref
array to update. The function doesn't the index anymore. It just
returns the number of added zones so that the caller can advance the
zonered array start for the next update.
This patch alone doesn't introduce any functional change yet, though, it
is merely a preparatory work for later changes.
Link: http://lkml.kernel.org/r/20170721143915.14161-7-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
try_online_node calls hotadd_new_pgdat which already calls
build_all_zonelists. So the additional call is redundant. Even though
hotadd_new_pgdat will only initialize zonelists of the new node this is
the right thing to do because such a node doesn't have any memory so
other zonelists would ignore all the zones from this node anyway.
Link: http://lkml.kernel.org/r/20170721143915.14161-6-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
build_all_zonelists gets a zone parameter to initialize zone's pagesets.
There is only a single user which gives a non-NULL zone parameter and
that one doesn't really need the rest of the build_all_zonelists (see
commit 6dcd73d701 ("memory-hotplug: allocate zone's pcp before
onlining pages")).
Therefore remove setup_zone_pageset from build_all_zonelists and call it
from its only user directly. This will also remove a pointless zonlists
rebuilding which is always good.
Link: http://lkml.kernel.org/r/20170721143915.14161-5-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__build_all_zonelists reinitializes each online cpu local node for
CONFIG_HAVE_MEMORYLESS_NODES. This makes sense because previously
memory less nodes could gain some memory during memory hotplug and so
the local node should be changed for CPUs close to such a node. It
makes less sense to do that unconditionally for a newly creaded NUMA
node which is still offline and without any memory.
Let's also simplify the cpu loop and use for_each_online_cpu instead of
an explicit cpu_online check for all possible cpus.
Link: http://lkml.kernel.org/r/20170721143915.14161-4-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
boot_pageset is a boot time hack which gets superseded by normal
pagesets later in the boot process. It makes zero sense to reinitialize
it again and again during memory hotplug.
Link: http://lkml.kernel.org/r/20170721143915.14161-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "cleanup zonelists initialization", v1.
This is aimed at cleaning up the zonelists initialization code we have
but the primary motivation was bug report [2] which got resolved but the
usage of stop_machine is just too ugly to live. Most patches are
straightforward but 3 of them need a special consideration.
Patch 1 removes zone ordered zonelists completely. I am CCing linux-api
because this is a user visible change. As I argue in the patch
description I do not think we have a strong usecase for it these days.
I have kept sysctl in place and warn into the log if somebody tries to
configure zone lists ordering. If somebody has a real usecase for it we
can revert this patch but I do not expect anybody will actually notice
runtime differences. This patch is not strictly needed for the rest but
it made patch 6 easier to implement.
Patch 7 removes stop_machine from build_all_zonelists without adding any
special synchronization between iterators and updater which I _believe_
is acceptable as explained in the changelog. I hope I am not missing
anything.
Patch 8 then removes zonelists_mutex which is kind of ugly as well and
not really needed AFAICS but a care should be taken when double checking
my thinking.
This patch (of 9):
Supporting zone ordered zonelists costs us just a lot of code while the
usefulness is arguable if existent at all. Mel has already made node
ordering default on 64b systems. 32b systems are still using
ZONELIST_ORDER_ZONE because it is considered better to fallback to a
different NUMA node rather than consume precious lowmem zones.
This argument is, however, weaken by the fact that the memory reclaim
has been reworked to be node rather than zone oriented. This means that
lowmem requests have to skip over all highmem pages on LRUs already and
so zone ordering doesn't save the reclaim time much. So the only
advantage of the zone ordering is under a light memory pressure when
highmem requests do not ever hit into lowmem zones and the lowmem
pressure doesn't need to reclaim.
Considering that 32b NUMA systems are rather suboptimal already and it
is generally advisable to use 64b kernel on such a HW I believe we
should rather care about the code maintainability and just get rid of
ZONELIST_ORDER_ZONE altogether. Keep systcl in place and warn if
somebody tries to set zone ordering either from kernel command line or
the sysctl.
[mhocko@suse.com: reading vm.numa_zonelist_order will never terminate]
Link: http://lkml.kernel.org/r/20170721143915.14161-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Cc: <linux-api@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Historically we have enforced that any kernel zone (e.g ZONE_NORMAL) has
to precede the Movable zone in the physical memory range. The purpose
of the movable zone is, however, not bound to any physical memory
restriction. It merely defines a class of migrateable and reclaimable
memory.
There are users (e.g. CMA) who might want to reserve specific physical
memory ranges for their own purpose. Moreover our pfn walkers have to
be prepared for zones overlapping in the physical range already because
we do support interleaving NUMA nodes and therefore zones can interleave
as well. This means we can allow each memory block to be associated
with a different zone.
Loosen the current onlining semantic and allow explicit onlining type on
any memblock. That means that online_{kernel,movable} will be allowed
regardless of the physical address of the memblock as long as it is
offline of course. This might result in moveble zone overlapping with
other kernel zones. Default onlining then becomes a bit tricky but
still sensible. echo online > memoryXY/state will online the given
block to
1) the default zone if the given range is outside of any zone
2) the enclosing zone if such a zone doesn't interleave with
any other zone
3) the default zone if more zones interleave for this range
where default zone is movable zone only if movable_node is enabled
otherwise it is a kernel zone.
Here is an example of the semantic with (movable_node is not present but
it work in an analogous way). We start with following memblocks, all of
them offline:
memory34/valid_zones:Normal Movable
memory35/valid_zones:Normal Movable
memory36/valid_zones:Normal Movable
memory37/valid_zones:Normal Movable
memory38/valid_zones:Normal Movable
memory39/valid_zones:Normal Movable
memory40/valid_zones:Normal Movable
memory41/valid_zones:Normal Movable
Now, we online block 34 in default mode and block 37 as movable
root@test1:/sys/devices/system/node/node1# echo online > memory34/state
root@test1:/sys/devices/system/node/node1# echo online_movable > memory37/state
memory34/valid_zones:Normal
memory35/valid_zones:Normal Movable
memory36/valid_zones:Normal Movable
memory37/valid_zones:Movable
memory38/valid_zones:Normal Movable
memory39/valid_zones:Normal Movable
memory40/valid_zones:Normal Movable
memory41/valid_zones:Normal Movable
As we can see all other blocks can still be onlined both into Normal and
Movable zones and the Normal is default because the Movable zone spans
only block37 now.
root@test1:/sys/devices/system/node/node1# echo online_movable > memory41/state
memory34/valid_zones:Normal
memory35/valid_zones:Normal Movable
memory36/valid_zones:Normal Movable
memory37/valid_zones:Movable
memory38/valid_zones:Movable Normal
memory39/valid_zones:Movable Normal
memory40/valid_zones:Movable Normal
memory41/valid_zones:Movable
Now the default zone for blocks 37-41 has changed because movable zone
spans that range.
root@test1:/sys/devices/system/node/node1# echo online_kernel > memory39/state
memory34/valid_zones:Normal
memory35/valid_zones:Normal Movable
memory36/valid_zones:Normal Movable
memory37/valid_zones:Movable
memory38/valid_zones:Normal Movable
memory39/valid_zones:Normal
memory40/valid_zones:Movable Normal
memory41/valid_zones:Movable
Note that the block 39 now belongs to the zone Normal and so block38
falls into Normal by default as well.
For completness
root@test1:/sys/devices/system/node/node1# for i in memory[34]?
do
echo online > $i/state 2>/dev/null
done
memory34/valid_zones:Normal
memory35/valid_zones:Normal
memory36/valid_zones:Normal
memory37/valid_zones:Movable
memory38/valid_zones:Normal
memory39/valid_zones:Normal
memory40/valid_zones:Movable
memory41/valid_zones:Movable
Implementation wise the change is quite straightforward. We can get rid
of allow_online_pfn_range altogether. online_pages allows only offline
nodes already. The original default_zone_for_pfn will become
default_kernel_zone_for_pfn. New default_zone_for_pfn implements the
above semantic. zone_for_pfn_range is slightly reorganized to implement
kernel and movable online type explicitly and MMOP_ONLINE_KEEP becomes a
catch all default behavior.
Link: http://lkml.kernel.org/r/20170714121233.16861-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Yasuaki Ishimatsu <yasu.isimatu@gmail.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Kani Toshimitsu <toshi.kani@hpe.com>
Cc: <slaoub@gmail.com>
Cc: Daniel Kiper <daniel.kiper@oracle.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: <linux-api@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Prior to commit f1dd2cd13c ("mm, memory_hotplug: do not associate
hotadded memory to zones until online") we used to allow to change the
valid zone types of a memory block if it is adjacent to a different zone
type.
This fact was reflected in memoryNN/valid_zones by the ordering of
printed zones. The first one was default (echo online > memoryNN/state)
and the other one could be onlined explicitly by online_{movable,kernel}.
This behavior was removed by the said patch and as such the ordering was
not all that important. In most cases a kernel zone would be default
anyway. The only exception is movable_node handled by "mm,
memory_hotplug: support movable_node for hotpluggable nodes".
Let's reintroduce this behavior again because later patch will remove
the zone overlap restriction and so user will be allowed to online
kernel resp. movable block regardless of its placement. Original
behavior will then become significant again because it would be
non-trivial for users to see what is the default zone to online into.
Implementation is really simple. Pull out zone selection out of
move_pfn_range into zone_for_pfn_range helper and use it in
show_valid_zones to display the zone for default onlining and then both
kernel and movable if they are allowed. Default online zone is not
duplicated.
Link: http://lkml.kernel.org/r/20170714121233.16861-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Reza Arbab <arbab@linux.vnet.ibm.com>
Cc: Yasuaki Ishimatsu <yasu.isimatu@gmail.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Kani Toshimitsu <toshi.kani@hpe.com>
Cc: <slaoub@gmail.com>
Cc: Daniel Kiper <daniel.kiper@oracle.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 9adb62a5df ("mm/hotplug: correctly setup fallback zonelists
when creating new pgdat") tries to build the correct zonelist for a
newly added node, while it is not necessary to rebuild it for already
exist nodes.
In build_zonelists(), it will iterate on nodes with memory. For a newly
added node, it will have memory until node_states_set_node() is called
in online_pages().
This patch avoids rebuilding the zonelists for already existing nodes.
build_zonelists_node() uses managed_zone(zone) checks, so it should not
include empty zones anyway. So effectively we avoid some pointless work
under stop_machine().
[akpm@linux-foundation.org: tweak comment text]
[akpm@linux-foundation.org: coding-style tweak, per Vlastimil]
Link: http://lkml.kernel.org/r/20170626035822.50155-1-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some shrinkers may only be able to free a bunch of objects at a time,
and so free more than the requested nr_to_scan in one pass.
Whilst other shrinkers may find themselves even unable to scan as many
objects as they counted, and so underreport. Account for the extra
freed/scanned objects against the total number of objects we intend to
scan, otherwise we may end up penalising the slab far more than
intended. Similarly, we want to add the underperforming scan to the
deferred pass so that we try harder and harder in future passes.
Link: http://lkml.kernel.org/r/20170822135325.9191-1-chris@chris-wilson.co.uk
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Shaohua Li <shli@fb.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add an assertion similar to "fasttop" check in GNU C Library allocator
as a part of SLAB_FREELIST_HARDENED feature. An object added to a
singly linked freelist should not point to itself. That helps to detect
some double free errors (e.g. CVE-2017-2636) without slub_debug and
KASAN.
Link: http://lkml.kernel.org/r/1502468246-1262-1-git-send-email-alex.popov@linux.com
Signed-off-by: Alexander Popov <alex.popov@linux.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Paul E McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tycho Andersen <tycho@docker.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This SLUB free list pointer obfuscation code is modified from Brad
Spengler/PaX Team's code in the last public patch of grsecurity/PaX
based on my understanding of the code. Changes or omissions from the
original code are mine and don't reflect the original grsecurity/PaX
code.
This adds a per-cache random value to SLUB caches that is XORed with
their freelist pointer address and value. This adds nearly zero
overhead and frustrates the very common heap overflow exploitation
method of overwriting freelist pointers.
A recent example of the attack is written up here:
http://cyseclabs.com/blog/cve-2016-6187-heap-off-by-one-exploit
and there is a section dedicated to the technique the book "A Guide to
Kernel Exploitation: Attacking the Core".
This is based on patches by Daniel Micay, and refactored to minimize the
use of #ifdef.
With 200-count cycles of "hackbench -g 20 -l 1000" I saw the following
run times:
before:
mean 10.11882499999999999995
variance .03320378329145728642
stdev .18221905304181911048
after:
mean 10.12654000000000000014
variance .04700556623115577889
stdev .21680767106160192064
The difference gets lost in the noise, but if the above is to be taken
literally, using CONFIG_FREELIST_HARDENED is 0.07% slower.
Link: http://lkml.kernel.org/r/20170802180609.GA66807@beast
Signed-off-by: Kees Cook <keescook@chromium.org>
Suggested-by: Daniel Micay <danielmicay@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Tycho Andersen <tycho@docker.com>
Cc: Alexander Popov <alex.popov@linux.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- free_kmem_cache_nodes() frees the cache node before nulling out a
reference to it
- init_kmem_cache_nodes() publishes the cache node before initializing
it
Neither of these matter at runtime because the cache nodes cannot be
looked up by any other thread. But it's neater and more consistent to
reorder these.
Link: http://lkml.kernel.org/r/20170707083408.40410-1-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that we no longer insert struct page pointers in DAX radix trees we
can remove the special casing for DAX in page_cache_tree_insert().
This also allows us to make dax_wake_mapping_entry_waiter() local to
fs/dax.c, removing it from dax.h.
Link: http://lkml.kernel.org/r/20170724170616.25810-5-ross.zwisler@linux.intel.com
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Suggested-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When servicing mmap() reads from file holes the current DAX code
allocates a page cache page of all zeroes and places the struct page
pointer in the mapping->page_tree radix tree. This has three major
drawbacks:
1) It consumes memory unnecessarily. For every 4k page that is read via
a DAX mmap() over a hole, we allocate a new page cache page. This
means that if you read 1GiB worth of pages, you end up using 1GiB of
zeroed memory.
2) It is slower than using a common zero page because each page fault
has more work to do. Instead of just inserting a common zero page we
have to allocate a page cache page, zero it, and then insert it.
3) The fact that we had to check for both DAX exceptional entries and
for page cache pages in the radix tree made the DAX code more
complex.
This series solves these issues by following the lead of the DAX PMD
code and using a common 4k zero page instead. This reduces memory usage
and decreases latencies for some workloads, and it simplifies the DAX
code, removing over 100 lines in total.
This patch (of 5):
To be able to use the common 4k zero page in DAX we need to have our PTE
fault path look more like our PMD fault path where a PTE entry can be
marked as dirty and writeable as it is first inserted rather than
waiting for a follow-up dax_pfn_mkwrite() => finish_mkwrite_fault()
call.
Right now we can rely on having a dax_pfn_mkwrite() call because we can
distinguish between these two cases in do_wp_page():
case 1: 4k zero page => writable DAX storage
case 2: read-only DAX storage => writeable DAX storage
This distinction is made by via vm_normal_page(). vm_normal_page()
returns false for the common 4k zero page, though, just as it does for
DAX ptes. Instead of special casing the DAX + 4k zero page case we will
simplify our DAX PTE page fault sequence so that it matches our DAX PMD
sequence, and get rid of the dax_pfn_mkwrite() helper. We will instead
use dax_iomap_fault() to handle write-protection faults.
This means that insert_pfn() needs to follow the lead of
insert_pfn_pmd() and allow us to pass in a 'mkwrite' flag. If 'mkwrite'
is set insert_pfn() will do the work that was previously done by
wp_page_reuse() as part of the dax_pfn_mkwrite() call path.
Link: http://lkml.kernel.org/r/20170724170616.25810-2-ross.zwisler@linux.intel.com
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull x86 mm changes from Ingo Molnar:
"PCID support, 5-level paging support, Secure Memory Encryption support
The main changes in this cycle are support for three new, complex
hardware features of x86 CPUs:
- Add 5-level paging support, which is a new hardware feature on
upcoming Intel CPUs allowing up to 128 PB of virtual address space
and 4 PB of physical RAM space - a 512-fold increase over the old
limits. (Supercomputers of the future forecasting hurricanes on an
ever warming planet can certainly make good use of more RAM.)
Many of the necessary changes went upstream in previous cycles,
v4.14 is the first kernel that can enable 5-level paging.
This feature is activated via CONFIG_X86_5LEVEL=y - disabled by
default.
(By Kirill A. Shutemov)
- Add 'encrypted memory' support, which is a new hardware feature on
upcoming AMD CPUs ('Secure Memory Encryption', SME) allowing system
RAM to be encrypted and decrypted (mostly) transparently by the
CPU, with a little help from the kernel to transition to/from
encrypted RAM. Such RAM should be more secure against various
attacks like RAM access via the memory bus and should make the
radio signature of memory bus traffic harder to intercept (and
decrypt) as well.
This feature is activated via CONFIG_AMD_MEM_ENCRYPT=y - disabled
by default.
(By Tom Lendacky)
- Enable PCID optimized TLB flushing on newer Intel CPUs: PCID is a
hardware feature that attaches an address space tag to TLB entries
and thus allows to skip TLB flushing in many cases, even if we
switch mm's.
(By Andy Lutomirski)
All three of these features were in the works for a long time, and
it's coincidence of the three independent development paths that they
are all enabled in v4.14 at once"
* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (65 commits)
x86/mm: Enable RCU based page table freeing (CONFIG_HAVE_RCU_TABLE_FREE=y)
x86/mm: Use pr_cont() in dump_pagetable()
x86/mm: Fix SME encryption stack ptr handling
kvm/x86: Avoid clearing the C-bit in rsvd_bits()
x86/CPU: Align CR3 defines
x86/mm, mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings of poison pages
acpi, x86/mm: Remove encryption mask from ACPI page protection type
x86/mm, kexec: Fix memory corruption with SME on successive kexecs
x86/mm/pkeys: Fix typo in Documentation/x86/protection-keys.txt
x86/mm/dump_pagetables: Speed up page tables dump for CONFIG_KASAN=y
x86/mm: Implement PCID based optimization: try to preserve old TLB entries using PCID
x86: Enable 5-level paging support via CONFIG_X86_5LEVEL=y
x86/mm: Allow userspace have mappings above 47-bit
x86/mm: Prepare to expose larger address space to userspace
x86/mpx: Do not allow MPX if we have mappings above 47-bit
x86/mm: Rename tasksize_32bit/64bit to task_size_32bit/64bit()
x86/xen: Redefine XEN_ELFNOTE_INIT_P2M using PUD_SIZE * PTRS_PER_PUD
x86/mm/dump_pagetables: Fix printout of p4d level
x86/mm/dump_pagetables: Generalize address normalization
x86/boot: Fix memremap() related build failure
...
Merge more fixes from Andrew Morton:
"6 fixes"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
scripts/dtc: fix '%zx' warning
include/linux/compiler.h: don't perform compiletime_assert with -O0
mm, madvise: ensure poisoned pages are removed from per-cpu lists
mm, uprobes: fix multiple free of ->uprobes_state.xol_area
kernel/kthread.c: kthread_worker: don't hog the cpu
mm,page_alloc: don't call __node_reclaim() with oom_lock held.
Wendy Wang reported off-list that a RAS HWPOISON-SOFT test case failed
and bisected it to the commit 479f854a20 ("mm, page_alloc: defer
debugging checks of pages allocated from the PCP").
The problem is that a page that was poisoned with madvise() is reused.
The commit removed a check that would trigger if DEBUG_VM was enabled
but re-enabling the check only fixes the problem as a side-effect by
printing a bad_page warning and recovering.
The root of the problem is that an madvise() can leave a poisoned page
on the per-cpu list. This patch drains all per-cpu lists after pages
are poisoned so that they will not be reused. Wendy reports that the
test case in question passes with this patch applied. While this could
be done in a targeted fashion, it is over-complicated for such a rare
operation.
Link: http://lkml.kernel.org/r/20170828133414.7qro57jbepdcyz5x@techsingularity.net
Fixes: 479f854a20 ("mm, page_alloc: defer debugging checks of pages allocated from the PCP")
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Reported-by: Wang, Wendy <wendy.wang@intel.com>
Tested-by: Wang, Wendy <wendy.wang@intel.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: "Hansen, Dave" <dave.hansen@intel.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We are doing a last second memory allocation attempt before calling
out_of_memory(). But since slab shrinker functions might indirectly
wait for other thread's __GFP_DIRECT_RECLAIM && !__GFP_NORETRY memory
allocations via sleeping locks, calling slab shrinker functions from
node_reclaim() from get_page_from_freelist() with oom_lock held has
possibility of deadlock. Therefore, make sure that last second memory
allocation attempt does not call slab shrinker functions.
Link: http://lkml.kernel.org/r/1503577106-9196-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The invalidate_page callback suffered from two pitfalls. First it used
to happen after the page table lock was release and thus a new page
might have setup before the call to invalidate_page() happened.
This is in a weird way fixed by commit c7ab0d2fdc ("mm: convert
try_to_unmap_one() to use page_vma_mapped_walk()") that moved the
callback under the page table lock but this also broke several existing
users of the mmu_notifier API that assumed they could sleep inside this
callback.
The second pitfall was invalidate_page() being the only callback not
taking a range of address in respect to invalidation but was giving an
address and a page. Lots of the callback implementers assumed this
could never be THP and thus failed to invalidate the appropriate range
for THP.
By killing this callback we unify the mmu_notifier callback API to
always take a virtual address range as input.
Finally this also simplifies the end user life as there is now two clear
choices:
- invalidate_range_start()/end() callback (which allow you to sleep)
- invalidate_range() where you can not sleep but happen right after
page table update under page table lock
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Bernhard Held <berny156@gmx.de>
Cc: Adam Borowski <kilobyte@angband.pl>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: axie <axie@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Replace all mmu_notifier_invalidate_page() calls by *_invalidate_range()
and make sure it is bracketed by calls to *_invalidate_range_start()/end().
Note that because we can not presume the pmd value or pte value we have
to assume the worst and unconditionaly report an invalidation as
happening.
Changed since v2:
- try_to_unmap_one() only one call to mmu_notifier_invalidate_range()
- compute end with PAGE_SIZE << compound_order(page)
- fix PageHuge() case in try_to_unmap_one()
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Bernhard Held <berny156@gmx.de>
Cc: Adam Borowski <kilobyte@angband.pl>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: axie <axie@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Replace all mmu_notifier_invalidate_page() calls by *_invalidate_range()
and make sure it is bracketed by calls to *_invalidate_range_start()/end().
Note that because we can not presume the pmd value or pte value we have
to assume the worst and unconditionaly report an invalidation as
happening.
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Bernhard Held <berny156@gmx.de>
Cc: Adam Borowski <kilobyte@angband.pl>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: axie <axie@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This reverts commit aac2fea94f.
It turns out that that patch was complete and utter garbage, and broke
KVM, resulting in odd oopses.
Quoting Andrea Arcangeli:
"The aforementioned commit has 3 bugs.
1) mmu_notifier_invalidate_range cannot be used in replacement of
mmu_notifier_invalidate_range_start/end.
For KVM mmu_notifier_invalidate_range is a noop and rightfully so.
A MMU notifier implementation has to implement either
->invalidate_range method or the invalidate_range_start/end
methods, not both. And if you implement invalidate_range_start/end
like KVM is forced to do, calling mmu_notifier_invalidate_range in
common code is a noop for KVM.
For those MMU notifiers that can get away only implementing
->invalidate_range, the ->invalidate_range is implicitly called by
mmu_notifier_invalidate_range_end(). And only those secondary MMUs
that share the same pagetable with the primary MMU (like AMD
iommuv2) can get away only implementing ->invalidate_range.
So all cases (THP on/off) are broken right now.
To fix this is enough to replace mmu_notifier_invalidate_range with
mmu_notifier_invalidate_range_start;mmu_notifier_invalidate_range_end.
Either that or call multiple mmu_notifier_invalidate_page like
before.
2) address + (1UL << compound_order(page) is buggy, it should be
PAGE_SIZE << compound_order(page), it's bytes not pages, 2M not
512.
3) The whole invalidate_range thing was an attempt to call a single
invalidate while walking multiple 4k ptes that maps the same THP
(after a pmd virtual split without physical compound page THP
split).
It's unclear if the rmap_walk will always provide an address that
is 2M aligned as parameter to try_to_unmap_one, in presence of THP.
I think it needs also an address &= (PAGE_SIZE <<
compound_order(page)) - 1 to be safe"
In general, we should stop making excuses for horrible MMU notifier
users. It's much more important that the core VM is sane and safe, than
letting MMU notifiers sleep.
So if some MMU notifier is sleeping under a spinlock, we need to fix the
notifier, not try to make excuses for that garbage in the core VM.
Reported-and-tested-by: Bernhard Held <berny156@gmx.de>
Reported-and-tested-by: Adam Borowski <kilobyte@angband.pl>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: axie <axie@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 3510ca20ec ("Minor page waitqueue cleanups") made the page
queue code always add new waiters to the back of the queue, which helps
upcoming patches to batch the wakeups for some horrid loads where the
wait queues grow to thousands of entries.
However, I forgot about the nasrt add_page_wait_queue() special case
code that is only used by the cachefiles code. That one still continued
to add the new wait queue entries at the beginning of the list.
Fix it, because any sane batched wakeup will require that we don't
suddenly start getting new entries at the beginning of the list that we
already handled in a previous batch.
[ The current code always does the whole list while holding the lock, so
wait queue ordering doesn't matter for correctness, but even then it's
better to add later entries at the end from a fairness standpoint ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The "lock_page_killable()" function waits for exclusive access to the
page lock bit using the WQ_FLAG_EXCLUSIVE bit in the waitqueue entry
set.
That means that if it gets woken up, other waiters may have been
skipped.
That, in turn, means that if it sees the page being unlocked, it *must*
take that lock and return success, even if a lethal signal is also
pending.
So instead of checking for lethal signals first, we need to check for
them after we've checked the actual bit that we were waiting for. Even
if that might then delay the killing of the process.
This matches the order of the old "wait_on_bit_lock()" infrastructure
that the page locking used to use (and is still used in a few other
areas).
Note that if we still return an error after having unsuccessfully tried
to acquire the page lock, that is ok: that means that some other thread
was able to get ahead of us and lock the page, and when that other
thread then unlocks the page, the wakeup event will be repeated. So any
other pending waiters will now get properly woken up.
Fixes: 6290602709 ("mm: add PageWaiters indicating tasks are waiting for a page bit")
Cc: Nick Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Jan Kara <jack@suse.cz>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tim Chen and Kan Liang have been battling a customer load that shows
extremely long page wakeup lists. The cause seems to be constant NUMA
migration of a hot page that is shared across a lot of threads, but the
actual root cause for the exact behavior has not been found.
Tim has a patch that batches the wait list traversal at wakeup time, so
that we at least don't get long uninterruptible cases where we traverse
and wake up thousands of processes and get nasty latency spikes. That
is likely 4.14 material, but we're still discussing the page waitqueue
specific parts of it.
In the meantime, I've tried to look at making the page wait queues less
expensive, and failing miserably. If you have thousands of threads
waiting for the same page, it will be painful. We'll need to try to
figure out the NUMA balancing issue some day, in addition to avoiding
the excessive spinlock hold times.
That said, having tried to rewrite the page wait queues, I can at least
fix up some of the braindamage in the current situation. In particular:
(a) we don't want to continue walking the page wait list if the bit
we're waiting for already got set again (which seems to be one of
the patterns of the bad load). That makes no progress and just
causes pointless cache pollution chasing the pointers.
(b) we don't want to put the non-locking waiters always on the front of
the queue, and the locking waiters always on the back. Not only is
that unfair, it means that we wake up thousands of reading threads
that will just end up being blocked by the writer later anyway.
Also add a comment about the layout of 'struct wait_page_key' - there is
an external user of it in the cachefiles code that means that it has to
match the layout of 'struct wait_bit_key' in the two first members. It
so happens to match, because 'struct page *' and 'unsigned long *' end
up having the same values simply because the page flags are the first
member in struct page.
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Christopher Lameter <cl@linux.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
/sys/kernel/mm/transparent_hugepage/shmem_enabled controls if we want
to allocate huge pages when allocate pages for private in-kernel shmem
mount.
Unfortunately, as Dan noticed, I've screwed it up and the only way to
make kernel allocate huge page for the mount is to use "force" there.
All other values will be effectively ignored.
Link: http://lkml.kernel.org/r/20170822144254.66431-1-kirill.shutemov@linux.intel.com
Fixes: 5a6e75f811 ("shmem: prepare huge= mount option and sysfs knob")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable <stable@vger.kernel.org> [4.8+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a problem that when counting the pages for creating the
hibernation snapshot will take significant amount of time, especially on
system with large memory. Since the counting job is performed with irq
disabled, this might lead to NMI lockup. The following warning were
found on a system with 1.5TB DRAM:
Freezing user space processes ... (elapsed 0.002 seconds) done.
OOM killer disabled.
PM: Preallocating image memory...
NMI watchdog: Watchdog detected hard LOCKUP on cpu 27
CPU: 27 PID: 3128 Comm: systemd-sleep Not tainted 4.13.0-0.rc2.git0.1.fc27.x86_64 #1
task: ffff9f01971ac000 task.stack: ffffb1a3f325c000
RIP: 0010:memory_bm_find_bit+0xf4/0x100
Call Trace:
swsusp_set_page_free+0x2b/0x30
mark_free_pages+0x147/0x1c0
count_data_pages+0x41/0xa0
hibernate_preallocate_memory+0x80/0x450
hibernation_snapshot+0x58/0x410
hibernate+0x17c/0x310
state_store+0xdf/0xf0
kobj_attr_store+0xf/0x20
sysfs_kf_write+0x37/0x40
kernfs_fop_write+0x11c/0x1a0
__vfs_write+0x37/0x170
vfs_write+0xb1/0x1a0
SyS_write+0x55/0xc0
entry_SYSCALL_64_fastpath+0x1a/0xa5
...
done (allocated 6590003 pages)
PM: Allocated 26360012 kbytes in 19.89 seconds (1325.28 MB/s)
It has taken nearly 20 seconds(2.10GHz CPU) thus the NMI lockup was
triggered. In case the timeout of the NMI watch dog has been set to 1
second, a safe interval should be 6590003/20 = 320k pages in theory.
However there might also be some platforms running at a lower frequency,
so feed the watchdog every 100k pages.
[yu.c.chen@intel.com: simplification]
Link: http://lkml.kernel.org/r/1503460079-29721-1-git-send-email-yu.c.chen@intel.com
[yu.c.chen@intel.com: use interval of 128k instead of 100k to avoid modulus]
Link: http://lkml.kernel.org/r/1503328098-5120-1-git-send-email-yu.c.chen@intel.com
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Reported-by: Jan Filipcewicz <jan.filipcewicz@intel.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Michal Hocko <mhocko@suse.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Len Brown <lenb@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The 'move_paghes()' system call was introduced long long ago with the
same permission checks as for sending a signal (except using
CAP_SYS_NICE instead of CAP_SYS_KILL for the overriding capability).
That turns out to not be a great choice - while the system call really
only moves physical page allocations around (and you need other
capabilities to do a lot of it), you can check the return value to map
out some the virtual address choices and defeat ASLR of a binary that
still shares your uid.
So change the access checks to the more common 'ptrace_may_access()'
model instead.
This tightens the access checks for the uid, and also effectively
changes the CAP_SYS_NICE check to CAP_SYS_PTRACE, but it's unlikely that
anybody really _uses_ this legacy system call any more (we hav ebetter
NUMA placement models these days), so I expect nobody to notice.
Famous last words.
Reported-by: Otto Ebeling <otto.ebeling@iki.fi>
Acked-by: Eric W. Biederman <ebiederm@xmission.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 19809c2da2 ("mm, vmalloc: use __GFP_HIGHMEM implicitly") added
use of __GFP_HIGHMEM for allocations. vmalloc_32 may use
GFP_DMA/GFP_DMA32 which does not play nice with __GFP_HIGHMEM and will
trigger a BUG in gfp_zone.
Only add __GFP_HIGHMEM if we aren't using GFP_DMA/GFP_DMA32.
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1482249
Link: http://lkml.kernel.org/r/20170816220705.31374-1-labbott@redhat.com
Fixes: 19809c2da2 ("mm, vmalloc: use __GFP_HIGHMEM implicitly")
Signed-off-by: Laura Abbott <labbott@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I hit a use after free issue when executing trinity and repoduced it
with KASAN enabled. The related call trace is as follows.
BUG: KASan: use after free in SyS_get_mempolicy+0x3c8/0x960 at addr ffff8801f582d766
Read of size 2 by task syz-executor1/798
INFO: Allocated in mpol_new.part.2+0x74/0x160 age=3 cpu=1 pid=799
__slab_alloc+0x768/0x970
kmem_cache_alloc+0x2e7/0x450
mpol_new.part.2+0x74/0x160
mpol_new+0x66/0x80
SyS_mbind+0x267/0x9f0
system_call_fastpath+0x16/0x1b
INFO: Freed in __mpol_put+0x2b/0x40 age=4 cpu=1 pid=799
__slab_free+0x495/0x8e0
kmem_cache_free+0x2f3/0x4c0
__mpol_put+0x2b/0x40
SyS_mbind+0x383/0x9f0
system_call_fastpath+0x16/0x1b
INFO: Slab 0xffffea0009cb8dc0 objects=23 used=8 fp=0xffff8801f582de40 flags=0x200000000004080
INFO: Object 0xffff8801f582d760 @offset=5984 fp=0xffff8801f582d600
Bytes b4 ffff8801f582d750: ae 01 ff ff 00 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a ........ZZZZZZZZ
Object ffff8801f582d760: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
Object ffff8801f582d770: 6b 6b 6b 6b 6b 6b 6b a5 kkkkkkk.
Redzone ffff8801f582d778: bb bb bb bb bb bb bb bb ........
Padding ffff8801f582d8b8: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ
Memory state around the buggy address:
ffff8801f582d600: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8801f582d680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801f582d700: fc fc fc fc fc fc fc fc fc fc fc fc fb fb fb fc
!shared memory policy is not protected against parallel removal by other
thread which is normally protected by the mmap_sem. do_get_mempolicy,
however, drops the lock midway while we can still access it later.
Early premature up_read is a historical artifact from times when
put_user was called in this path see https://lwn.net/Articles/124754/
but that is gone since 8bccd85ffb ("[PATCH] Implement sys_* do_*
layering in the memory policy layer."). but when we have the the
current mempolicy ref count model. The issue was introduced
accordingly.
Fix the issue by removing the premature release.
Link: http://lkml.kernel.org/r/1502950924-27521-1-git-send-email-zhongjiang@huawei.com
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: <stable@vger.kernel.org> [2.6+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
name[] in cma_debugfs_add_one() can only accommodate 16 chars including
NULL to store sprintf output. It's common for cma device name to be
larger than 15 chars. This can cause stack corrpution. If the gcc
stack protector is turned on, this can cause a panic due to stack
corruption.
Below is one example trace:
Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in:
ffffff8e69a75730
Call trace:
dump_backtrace+0x0/0x2c4
show_stack+0x20/0x28
dump_stack+0xb8/0xf4
panic+0x154/0x2b0
print_tainted+0x0/0xc0
cma_debugfs_init+0x274/0x290
do_one_initcall+0x5c/0x168
kernel_init_freeable+0x1c8/0x280
Fix the short sprintf buffer in cma_debugfs_add_one() by using
scnprintf() instead of sprintf().
Link: http://lkml.kernel.org/r/1502446217-21840-1-git-send-email-guptap@codeaurora.org
Fixes: f318dd083c ("cma: Store a name in the cma structure")
Signed-off-by: Prakash Gupta <guptap@codeaurora.org>
Acked-by: Laura Abbott <labbott@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Wenwei Tao has noticed that our current assumption that the oom victim
is dying and never doing any visible changes after it dies, and so the
oom_reaper can tear it down, is not entirely true.
__task_will_free_mem consider a task dying when SIGNAL_GROUP_EXIT is set
but do_group_exit sends SIGKILL to all threads _after_ the flag is set.
So there is a race window when some threads won't have
fatal_signal_pending while the oom_reaper could start unmapping the
address space. Moreover some paths might not check for fatal signals
before each PF/g-u-p/copy_from_user.
We already have a protection for oom_reaper vs. PF races by checking
MMF_UNSTABLE. This has been, however, checked only for kernel threads
(use_mm users) which can outlive the oom victim. A simple fix would be
to extend the current check in handle_mm_fault for all tasks but that
wouldn't be sufficient because the current check assumes that a kernel
thread would bail out after EFAULT from get_user*/copy_from_user and
never re-read the same address which would succeed because the PF path
has established page tables already. This seems to be the case for the
only existing use_mm user currently (virtio driver) but it is rather
fragile in general.
This is even more fragile in general for more complex paths such as
generic_perform_write which can re-read the same address more times
(e.g. iov_iter_copy_from_user_atomic to fail and then
iov_iter_fault_in_readable on retry).
Therefore we have to implement MMF_UNSTABLE protection in a robust way
and never make a potentially corrupted content visible. That requires
to hook deeper into the PF path and check for the flag _every time_
before a pte for anonymous memory is established (that means all
!VM_SHARED mappings).
The corruption can be triggered artificially
(http://lkml.kernel.org/r/201708040646.v746kkhC024636@www262.sakura.ne.jp)
but there doesn't seem to be any real life bug report. The race window
should be quite tight to trigger most of the time.
Link: http://lkml.kernel.org/r/20170807113839.16695-3-mhocko@kernel.org
Fixes: aac4536355 ("mm, oom: introduce oom reaper")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Wenwei Tao <wenwei.tww@alibaba-inc.com>
Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andrea Argangeli <andrea@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Tetsuo Handa has noticed that MMF_UNSTABLE SIGBUS path in
handle_mm_fault causes a lockdep splat
Out of memory: Kill process 1056 (a.out) score 603 or sacrifice child
Killed process 1056 (a.out) total-vm:4268108kB, anon-rss:2246048kB, file-rss:0kB, shmem-rss:0kB
a.out (1169) used greatest stack depth: 11664 bytes left
DEBUG_LOCKS_WARN_ON(depth <= 0)
------------[ cut here ]------------
WARNING: CPU: 6 PID: 1339 at kernel/locking/lockdep.c:3617 lock_release+0x172/0x1e0
CPU: 6 PID: 1339 Comm: a.out Not tainted 4.13.0-rc3-next-20170803+ #142
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/02/2015
RIP: 0010:lock_release+0x172/0x1e0
Call Trace:
up_read+0x1a/0x40
__do_page_fault+0x28e/0x4c0
do_page_fault+0x30/0x80
page_fault+0x28/0x30
The reason is that the page fault path might have dropped the mmap_sem
and returned with VM_FAULT_RETRY. MMF_UNSTABLE check however rewrites
the error path to VM_FAULT_SIGBUS and we always expect mmap_sem taken in
that path. Fix this by taking mmap_sem when VM_FAULT_RETRY is held in
the MMF_UNSTABLE path.
We cannot simply add VM_FAULT_SIGBUS to the existing error code because
all arch specific page fault handlers and g-u-p would have to learn a
new error code combination.
Link: http://lkml.kernel.org/r/20170807113839.16695-2-mhocko@kernel.org
Fixes: 3f70dc38ce ("mm: make sure that kthreads will not refault oom reaped memory")
Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Andrea Argangeli <andrea@kernel.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Wenwei Tao <wenwei.tww@alibaba-inc.com>
Cc: <stable@vger.kernel.org> [4.9+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
