If a cgroup violates its memory.high constraints, we may end up unduly
penalising it. For example, for the following hierarchy:
A: max high, 20 usage
A/B: 9 high, 10 usage
A/C: max high, 10 usage
We would end up doing the following calculation below when calculating
high delay for A/B:
A/B: 10 - 9 = 1...
A: 20 - PAGE_COUNTER_MAX = 21, so set max_overage to 21.
This gets worse with higher disparities in usage in the parent.
I have no idea how this disappeared from the final version of the patch,
but it is certainly Not Good(tm). This wasn't obvious in testing because,
for a simple cgroup hierarchy with only one child, the result is usually
roughly the same. It's only in more complex hierarchies that things go
really awry (although still, the effects are limited to a maximum of 2
seconds in schedule_timeout_killable at a maximum).
[chris@chrisdown.name: changelog]
Fixes: e26733e0d0 ("mm, memcg: throttle allocators based on ancestral memory.high")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Chris Down <chris@chrisdown.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org> [5.4.x]
Link: http://lkml.kernel.org/r/20200331152424.GA1019937@chrisdown.name
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Add support for region alignment configuration and enforcement to
fix compatibility across architectures and PowerPC page size
configurations.
- Introduce 'zero_page_range' as a dax operation. This facilitates
filesystem-dax operation without a block-device.
- Introduce phys_to_target_node() to facilitate drivers that want to
know resulting numa node if a given reserved address range was
onlined.
- Advertise a persistence-domain for of_pmem and papr_scm. The
persistence domain indicates where cpu-store cycles need to reach in
the platform-memory subsystem before the platform will consider them
power-fail protected.
- Promote numa_map_to_online_node() to a cross-kernel generic facility.
- Save x86 numa information to allow for node-id lookups for reserved
memory ranges, deploy that capability for the e820-pmem driver.
- Pick up some miscellaneous minor fixes, that missed v5.6-final,
including a some smatch reports in the ioctl path and some unit test
compilation fixups.
- Fixup some flexible-array declarations.
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Merge tag 'libnvdimm-for-5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm
Pull libnvdimm and dax updates from Dan Williams:
"There were multiple touches outside of drivers/nvdimm/ this round to
add cross arch compatibility to the devm_memremap_pages() interface,
enhance numa information for persistent memory ranges, and add a
zero_page_range() dax operation.
This cycle I switched from the patchwork api to Konstantin's b4 script
for collecting tags (from x86, PowerPC, filesystem, and device-mapper
folks), and everything looks to have gone ok there. This has all
appeared in -next with no reported issues.
Summary:
- Add support for region alignment configuration and enforcement to
fix compatibility across architectures and PowerPC page size
configurations.
- Introduce 'zero_page_range' as a dax operation. This facilitates
filesystem-dax operation without a block-device.
- Introduce phys_to_target_node() to facilitate drivers that want to
know resulting numa node if a given reserved address range was
onlined.
- Advertise a persistence-domain for of_pmem and papr_scm. The
persistence domain indicates where cpu-store cycles need to reach
in the platform-memory subsystem before the platform will consider
them power-fail protected.
- Promote numa_map_to_online_node() to a cross-kernel generic
facility.
- Save x86 numa information to allow for node-id lookups for reserved
memory ranges, deploy that capability for the e820-pmem driver.
- Pick up some miscellaneous minor fixes, that missed v5.6-final,
including a some smatch reports in the ioctl path and some unit
test compilation fixups.
- Fixup some flexible-array declarations"
* tag 'libnvdimm-for-5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: (29 commits)
dax: Move mandatory ->zero_page_range() check in alloc_dax()
dax,iomap: Add helper dax_iomap_zero() to zero a range
dax: Use new dax zero page method for zeroing a page
dm,dax: Add dax zero_page_range operation
s390,dcssblk,dax: Add dax zero_page_range operation to dcssblk driver
dax, pmem: Add a dax operation zero_page_range
pmem: Add functions for reading/writing page to/from pmem
libnvdimm: Update persistence domain value for of_pmem and papr_scm device
tools/test/nvdimm: Fix out of tree build
libnvdimm/region: Fix build error
libnvdimm/region: Replace zero-length array with flexible-array member
libnvdimm/label: Replace zero-length array with flexible-array member
ACPI: NFIT: Replace zero-length array with flexible-array member
libnvdimm/region: Introduce an 'align' attribute
libnvdimm/region: Introduce NDD_LABELING
libnvdimm/namespace: Enforce memremap_compat_align()
libnvdimm/pfn: Prevent raw mode fallback if pfn-infoblock valid
libnvdimm: Out of bounds read in __nd_ioctl()
acpi/nfit: improve bounds checking for 'func'
mm/memremap_pages: Introduce memremap_compat_align()
...
__get_user_pages_locked() will return 0 instead of -EINTR after commit
4426e945df ("mm/gup: allow VM_FAULT_RETRY for multiple times") which
added extra code to allow gup detect fatal signal faster.
Restore the original -EINTR behavior.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Fixes: 4426e945df ("mm/gup: allow VM_FAULT_RETRY for multiple times")
Reported-by: syzbot+3be1a33f04dc782e9fd5@syzkaller.appspotmail.com
Signed-off-by: Hillf Danton <hdanton@sina.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It's definitely incorrect to mark the lock as taken even if
down_read_killable() failed.
This wass overlooked when we switched from down_read() to
down_read_killable() because down_read() won't fail while
down_read_killable() could.
Fixes: 71335f37c5 ("mm/gup: allow to react to fatal signals")
Reported-by: syzbot+a8c70b7f3579fc0587dc@syzkaller.appspotmail.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
lookup_node() uses gup to pin the page and get node information. It
checks against ret>=0 assuming the page will be filled in. However it's
also possible that gup will return zero, for example, when the thread is
quickly killed with a fatal signal. Teach lookup_node() to gracefully
return an error -EFAULT if it happens.
Meanwhile, initialize "page" to NULL to avoid potential risk of
exploiting the pointer.
Fixes: 4426e945df ("mm/gup: allow VM_FAULT_RETRY for multiple times")
Reported-by: syzbot+693dc11fcb53120b5559@syzkaller.appspotmail.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
filter_irq_stacks() can be used by other tools (e.g. KMSAN), so it needs
to be moved to a common location. lib/stackdepot.c seems a good place, as
filter_irq_stacks() is usually applied to the output of
stack_trace_save().
This patch has been previously mailed as part of KMSAN RFC patch series.
[glider@google.co: nds32: linker script: add SOFTIRQENTRY_TEXT\
Link: http://lkml.kernel.org/r/20200311121002.241430-1-glider@google.com
[glider@google.com: add IRQENTRY_TEXT and SOFTIRQENTRY_TEXT to linker script]
Link: http://lkml.kernel.org/r/20200311121124.243352-1-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Link: http://lkml.kernel.org/r/20200220141916.55455-3-glider@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that "struct proc_ops" exist we can start putting there stuff which
could not fly with VFS "struct file_operations"...
Most of fs/proc/inode.c file is dedicated to make open/read/.../close
reliable in the event of disappearing /proc entries which usually happens
if module is getting removed. Files like /proc/cpuinfo which never
disappear simply do not need such protection.
Save 2 atomic ops, 1 allocation, 1 free per open/read/close sequence for such
"permanent" files.
Enable "permanent" flag for
/proc/cpuinfo
/proc/kmsg
/proc/modules
/proc/slabinfo
/proc/stat
/proc/sysvipc/*
/proc/swaps
More will come once I figure out foolproof way to prevent out module
authors from marking their stuff "permanent" for performance reasons
when it is not.
This should help with scalability: benchmark is "read /proc/cpuinfo R times
by N threads scattered over the system".
N R t, s (before) t, s (after)
-----------------------------------------------------
64 4096 1.582458 1.530502 -3.2%
256 4096 6.371926 6.125168 -3.9%
1024 4096 25.64888 24.47528 -4.6%
Benchmark source:
#include <chrono>
#include <iostream>
#include <thread>
#include <vector>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
const int NR_CPUS = sysconf(_SC_NPROCESSORS_ONLN);
int N;
const char *filename;
int R;
int xxx = 0;
int glue(int n)
{
cpu_set_t m;
CPU_ZERO(&m);
CPU_SET(n, &m);
return sched_setaffinity(0, sizeof(cpu_set_t), &m);
}
void f(int n)
{
glue(n % NR_CPUS);
while (*(volatile int *)&xxx == 0) {
}
for (int i = 0; i < R; i++) {
int fd = open(filename, O_RDONLY);
char buf[4096];
ssize_t rv = read(fd, buf, sizeof(buf));
asm volatile ("" :: "g" (rv));
close(fd);
}
}
int main(int argc, char *argv[])
{
if (argc < 4) {
std::cerr << "usage: " << argv[0] << ' ' << "N /proc/filename R
";
return 1;
}
N = atoi(argv[1]);
filename = argv[2];
R = atoi(argv[3]);
for (int i = 0; i < NR_CPUS; i++) {
if (glue(i) == 0)
break;
}
std::vector<std::thread> T;
T.reserve(N);
for (int i = 0; i < N; i++) {
T.emplace_back(f, i);
}
auto t0 = std::chrono::system_clock::now();
{
*(volatile int *)&xxx = 1;
for (auto& t: T) {
t.join();
}
}
auto t1 = std::chrono::system_clock::now();
std::chrono::duration<double> dt = t1 - t0;
std::cout << dt.count() << '
';
return 0;
}
P.S.:
Explicit randomization marker is added because adding non-function pointer
will silently disable structure layout randomization.
[akpm@linux-foundation.org: coding style fixes]
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Joe Perches <joe@perches.com>
Link: http://lkml.kernel.org/r/20200222201539.GA22576@avx2
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Previously there was a check if 'size' is aligned to 'align' and if not
then it was aligned. This check was expensive as both branch and division
are expensive instructions in most architectures. 'ALIGN' function on
already aligned value will not change it, and as it is cheaper than branch
+ division it can be executed all the time and branch can be removed.
Signed-off-by: Mateusz Nosek <mateusznosek0@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200320173317.26408-1-mateusznosek0@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
MAX_ZONELISTS is a compile time constant, so it should be compared using
BUILD_BUG_ON not BUG_ON.
Signed-off-by: Mateusz Nosek <mateusznosek0@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Link: http://lkml.kernel.org/r/20200228224617.11343-1-mateusznosek0@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The parameter of remap_pfn_range() @pfn passed from the caller is actually
a page-frame number converted by corresponding physical address of kernel
memory, the original comment is ambiguous that may mislead the users.
Meanwhile, there is an ambiguous typo "VMM" in the comment of
vm_area_struct. So fixing them will make the code more readable.
Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1583026921-15279-1-git-send-email-qiwuchen55@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Sparse reports a warning at unpin_tag()()
warning: context imbalance in unpin_tag() - unexpected unlock
The root cause is the missing annotation at unpin_tag()
Add the missing __releases(bitlock) annotation
Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Link: http://lkml.kernel.org/r/20200214204741.94112-14-jbi.octave@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Sparse reports a warning at pin_tag()()
warning: context imbalance in pin_tag() - wrong count at exit
The root cause is the missing annotation at pin_tag()
Add the missing __acquires(bitlock) annotation
Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Link: http://lkml.kernel.org/r/20200214204741.94112-13-jbi.octave@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Sparse reports a warning at migrate_read_unlock()()
warning: context imbalance in migrate_read_unlock() - unexpected unlock
The root cause is the missing annotation at migrate_read_unlock()
Add the missing __releases(&zspage->lock) annotation
Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Link: http://lkml.kernel.org/r/20200214204741.94112-12-jbi.octave@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Sparse reports a warning at migrate_read_lock()()
warning: context imbalance in migrate_read_lock() - wrong count at exit
The root cause is the missing annotation at migrate_read_lock()
Add the missing __acquires(&zspage->lock) annotation
Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Link: http://lkml.kernel.org/r/20200214204741.94112-11-jbi.octave@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Sparse reports a warning at put_map()()
warning: context imbalance in put_map() - unexpected unlock
The root cause is the missing annotation at put_map()
Add the missing __releases(&object_map_lock) annotation
Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200214204741.94112-10-jbi.octave@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Sparse reports a warning at get_map()()
warning: context imbalance in get_map() - wrong count at exit
The root cause is the missing annotation at get_map()
Add the missing __acquires(&object_map_lock) annotation
Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200214204741.94112-9-jbi.octave@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Sparse reports a warning at queue_pages_pmd()
context imbalance in queue_pages_pmd() - unexpected unlock
The root cause is the missing annotation at queue_pages_pmd()
Add the missing __releases(ptl)
Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200214204741.94112-8-jbi.octave@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Sparse reports a warning at gather_surplus_pages()
warning: context imbalance in hugetlb_cow() - unexpected unlock
The root cause is the missing annotation at gather_surplus_pages()
Add the missing __must_hold(&hugetlb_lock)
Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Link: http://lkml.kernel.org/r/20200214204741.94112-7-jbi.octave@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Sparse reports a warning at compact_lock_irqsave()
warning: context imbalance in compact_lock_irqsave() - wrong count at exit
The root cause is the missing annotation at compact_lock_irqsave()
Add the missing __acquires(lock) annotation.
Signed-off-by: Jules Irenge <jbi.octave@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200214204741.94112-6-jbi.octave@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The compressed cache for swap pages (zswap) currently needs from 1 to 3
extra kernel command line parameters in order to make it work: it has to
be enabled by adding a "zswap.enabled=1" command line parameter and if one
wants a different compressor or pool allocator than the default lzo / zbud
combination then these choices also need to be specified on the kernel
command line in additional parameters.
Using a different compressor and allocator for zswap is actually pretty
common as guides often recommend using the lz4 / z3fold pair instead of
the default one. In such case it is also necessary to remember to enable
the appropriate compression algorithm and pool allocator in the kernel
config manually.
Let's avoid the need for adding these kernel command line parameters and
automatically pull in the dependencies for the selected compressor
algorithm and pool allocator by adding an appropriate default switches to
Kconfig.
The default values for these options match what the code was using
previously as its defaults.
Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Vitaly Wool <vitaly.wool@konsulko.com>
Link: http://lkml.kernel.org/r/20200202000112.456103-1-mail@maciej.szmigiero.name
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I recently build the RISC-V port with LLVM trunk, which has introduced a
new warning when casting from a pointer to an enum of a smaller size.
This patch simply casts to a long in the middle to stop the warning. I'd
be surprised this is the only one in the kernel, but it's the only one I
saw.
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20200227211741.83165-1-palmer@dabbelt.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Yang Shi writes:
Currently, when truncating a shmem file, if the range is partly in a THP
(start or end is in the middle of THP), the pages actually will just get
cleared rather than being freed, unless the range covers the whole THP.
Even though all the subpages are truncated (randomly or sequentially), the
THP may still be kept in page cache.
This might be fine for some usecases which prefer preserving THP, but
balloon inflation is handled in base page size. So when using shmem THP
as memory backend, QEMU inflation actually doesn't work as expected since
it doesn't free memory. But the inflation usecase really needs to get the
memory freed. (Anonymous THP will also not get freed right away, but will
be freed eventually when all subpages are unmapped: whereas shmem THP
still stays in page cache.)
Split THP right away when doing partial hole punch, and if split fails
just clear the page so that read of the punched area will return zeroes.
Hugh Dickins adds:
Our earlier "team of pages" huge tmpfs implementation worked in the way
that Yang Shi proposes; and we have been using this patch to continue to
split the huge page when hole-punched or truncated, since converting over
to the compound page implementation. Although huge tmpfs gives out huge
pages when available, if the user specifically asks to truncate or punch a
hole (perhaps to free memory, perhaps to reduce the memcg charge), then
the filesystem should do so as best it can, splitting the huge page.
That is not always possible: any additional reference to the huge page
prevents split_huge_page() from succeeding, so the result can be flaky.
But in practice it works successfully enough that we've not seen any
problem from that.
Add shmem_punch_compound() to encapsulate the decision of when a split is
needed, and doing the split if so. Using this simplifies the flow in
shmem_undo_range(); and the first (trylock) pass does not need to do any
page clearing on failure, because the second pass will either succeed or
do that clearing. Following the example of zero_user_segment() when
clearing a partial page, add flush_dcache_page() and set_page_dirty() when
clearing a hole - though I'm not certain that either is needed.
But: split_huge_page() would be sure to fail if shmem_undo_range()'s
pagevec holds further references to the huge page. The easiest way to fix
that is for find_get_entries() to return early, as soon as it has put one
compound head or tail into the pagevec. At first this felt like a hack;
but on examination, this convention better suits all its callers - or will
do, if the slight one-page-per-pagevec slowdown in shmem_unlock_mapping()
and shmem_seek_hole_data() is transformed into a 512-page-per-pagevec
speedup by checking for compound pages there.
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2002261959020.10801@eggly.anvils
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Previously 0 was assigned to variable 'error' but the variable was never
read before reassignemnt later. So the assignment can be removed.
Signed-off-by: Mateusz Nosek <mateusznosek0@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Link: http://lkml.kernel.org/r/20200301152832.24595-1-mateusznosek0@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Variables declared in a switch statement before any case statements cannot
be automatically initialized with compiler instrumentation (as they are
not part of any execution flow). With GCC's proposed automatic stack
variable initialization feature, this triggers a warning (and they don't
get initialized). Clang's automatic stack variable initialization (via
CONFIG_INIT_STACK_ALL=y) doesn't throw a warning, but it also doesn't
initialize such variables[1]. Note that these warnings (or silent
skipping) happen before the dead-store elimination optimization phase, so
even when the automatic initializations are later elided in favor of
direct initializations, the warnings remain.
To avoid these problems, move such variables into the "case" where they're
used or lift them up into the main function body.
mm/shmem.c: In function `shmem_getpage_gfp':
mm/shmem.c:1816:10: warning: statement will never be executed [-Wswitch-unreachable]
1816 | loff_t i_size;
| ^~~~~~
[1] https://bugs.llvm.org/show_bug.cgi?id=44916
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Alexander Potapenko <glider@google.com>
Link: http://lkml.kernel.org/r/20200220062312.69165-1-keescook@chromium.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use __pfn_to_section() API instead of open-coding for better code
readability.
Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: David Hildenbrand <david@redhat.com>
Link: http://lkml.kernel.org/r/1584345134-16671-1-git-send-email-qiwuchen55@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For now, distributions implement advanced udev rules to essentially
- Don't online any hotplugged memory (s390x)
- Online all memory to ZONE_NORMAL (e.g., most virt environments like
hyperv)
- Online all memory to ZONE_MOVABLE in case the zone imbalance is taken
care of (e.g., bare metal, special virt environments)
In summary: All memory is usually onlined the same way, however, the
kernel always has to ask user space to come up with the same answer.
E.g., Hyper-V always waits for a memory block to get onlined before
continuing, otherwise it might end up adding memory faster than
onlining it, which can result in strange OOM situations. This waiting
slows down adding of a bigger amount of memory.
Let's allow to specify a default online_type, not just "online" and
"offline". This allows distributions to configure the default online_type
when booting up and be done with it.
We can now specify "offline", "online", "online_movable" and
"online_kernel" via
- "memhp_default_state=" on the kernel cmdline
- /sys/devices/system/memory/auto_online_blocks
just like we are able to specify for a single memory block via
/sys/devices/system/memory/memoryX/state
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Yumei Huang <yuhuang@redhat.com>
Link: http://lkml.kernel.org/r/20200317104942.11178-9-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
... and rename it to memhp_default_online_type. This is a preparation
for more detailed default online behavior.
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Yumei Huang <yuhuang@redhat.com>
Link: http://lkml.kernel.org/r/20200317104942.11178-8-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
All in-tree users except the mm-core are gone. Let's drop the export.
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Baoquan He <bhe@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Yumei Huang <yuhuang@redhat.com>
Link: http://lkml.kernel.org/r/20200317104942.11178-7-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
No functional change.
[bhe@redhat.com: move functions into CONFIG_MEMORY_HOTPLUG ifdeffery scope]
Link: http://lkml.kernel.org/r/20200316045804.GC3486@MiWiFi-R3L-srv
Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: http://lkml.kernel.org/r/20200312124414.439-6-bhe@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
And tell check_pfn_span() gating the porper alignment and size of hot
added memory region.
And also move the code comments from inside section_deactivate() to being
above it. The code comments are reasonable for the whole function, and
the moving makes code cleaner.
Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Link: http://lkml.kernel.org/r/20200312124414.439-5-bhe@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, to support subsection aligned memory region adding for pmem,
subsection map is added to track which subsection is present.
However, config ZONE_DEVICE depends on SPARSEMEM_VMEMMAP. It means
subsection map only makes sense when SPARSEMEM_VMEMMAP enabled. For the
classic sparse, it's meaningless. Even worse, it may confuse people when
checking code related to the classic sparse.
About the classic sparse which doesn't support subsection hotplug, Dan
said it's more because the effort and maintenance burden outweighs the
benefit. Besides, the current 64 bit ARCHes all enable
SPARSEMEM_VMEMMAP_ENABLE by default.
Combining the above reasons, no need to provide subsection map and the
relevant handling for the classic sparse. Let's remove them.
Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Link: http://lkml.kernel.org/r/20200312124414.439-4-bhe@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Factor out the code which clear subsection map of one memory region from
section_deactivate() into clear_subsection_map().
And also add helper function is_subsection_map_empty() to check if the
current subsection map is empty or not.
Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Link: http://lkml.kernel.org/r/20200312124414.439-3-bhe@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm/hotplug: Only use subsection map for VMEMMAP", v4.
Memory sub-section hotplug was added to fix the issue that nvdimm could be
mapped at non-section aligned starting address. A subsection map is added
into struct mem_section_usage to implement it.
However, config ZONE_DEVICE depends on SPARSEMEM_VMEMMAP. It means
subsection map only makes sense when SPARSEMEM_VMEMMAP enabled. For the
classic sparse, subsection map is meaningless and confusing.
About the classic sparse which doesn't support subsection hotplug, Dan
said it's more because the effort and maintenance burden outweighs the
benefit. Besides, the current 64 bit ARCHes all enable
SPARSEMEM_VMEMMAP_ENABLE by default.
This patch (of 5):
Factor out the code that fills the subsection map from section_activate()
into fill_subsection_map(), this makes section_activate() cleaner and
easier to follow.
Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Link: http://lkml.kernel.org/r/20200312124414.439-2-bhe@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Let's drop the basically unused section stuff and simplify. The logic now
matches the logic in __remove_pages().
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Link: http://lkml.kernel.org/r/20200228095819.10750-3-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In commit 52fb87c81f ("mm/memory_hotplug: cleanup __remove_pages()"), we
cleaned up __remove_pages(), and introduced a shorter variant to calculate
the number of pages to the next section boundary.
Turns out we can make this calculation easier to read. We always want to
have the number of pages (> 0) to the next section boundary, starting from
the current pfn.
We'll clean up __remove_pages() in a follow-up patch and directly make use
of this computation.
Suggested-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Link: http://lkml.kernel.org/r/20200228095819.10750-2-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In commit 357b4da50a ("x86: respect memory size limiting via mem=
parameter") a global varialbe max_mem_size is added to store the value
parsed from 'mem= ', then checked when memory region is added. This truly
stops those DIMMs from being added into system memory during boot-time.
However, it also limits the later memory hotplug functionality. Any DIMM
can't be hotplugged any more if its region is beyond the max_mem_size. We
will get errors like:
[ 216.387164] acpi PNP0C80:02: add_memory failed
[ 216.389301] acpi PNP0C80:02: acpi_memory_enable_device() error
[ 216.392187] acpi PNP0C80:02: Enumeration failure
This will cause issue in a known use case where 'mem=' is added to the
hypervisor. The memory that lies after 'mem=' boundary will be assigned
to KVM guests. After commit 357b4da50a merged, memory can't be extended
dynamically if system memory on hypervisor is not sufficient.
So fix it by also checking if it's during boot-time restricting to add
memory. Otherwise, skip the restriction.
And also add this use case to document of 'mem=' kernel parameter.
Fixes: 357b4da50a ("x86: respect memory size limiting via mem= parameter")
Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Link: http://lkml.kernel.org/r/20200204050643.20925-1-bhe@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit c5e79ef561 ("mm/memory_hotplug.c: don't allow to
online/offline memory blocks with holes") we disallow to offline any
memory with holes. As all boot memory is online and hotplugged memory
cannot contain holes, we never online memory with holes.
This present check can be dropped.
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Link: http://lkml.kernel.org/r/20200127110424.5757-4-david@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add API to enable/disable writeprotect a vma range. Unlike mprotect, this
doesn't split/merge vmas.
[peterx@redhat.com:
- use the helper to find VMA;
- return -ENOENT if not found to match mcopy case;
- use the new MM_CP_UFFD_WP* flags for change_protection
- check against mmap_changing for failures
- replace find_dst_vma with vma_find_uffd]
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Martin Cracauer <cracauer@cons.org>
Cc: Marty McFadden <mcfadden8@llnl.gov>
Cc: Maya Gokhale <gokhale2@llnl.gov>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Link: http://lkml.kernel.org/r/20200220163112.11409-13-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Don't collapse the huge PMD if there is any userfault write protected
small PTEs. The problem is that the write protection is in small page
granularity and there's no way to keep all these write protection
information if the small pages are going to be merged into a huge PMD.
The same thing needs to be considered for swap entries and migration
entries. So do the check as well disregarding khugepaged_max_ptes_swap.
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Martin Cracauer <cracauer@cons.org>
Cc: Marty McFadden <mcfadden8@llnl.gov>
Cc: Maya Gokhale <gokhale2@llnl.gov>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shli@fb.com>
Link: http://lkml.kernel.org/r/20200220163112.11409-12-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For either swap and page migration, we all use the bit 2 of the entry to
identify whether this entry is uffd write-protected. It plays a similar
role as the existing soft dirty bit in swap entries but only for keeping
the uffd-wp tracking for a specific PTE/PMD.
Something special here is that when we want to recover the uffd-wp bit
from a swap/migration entry to the PTE bit we'll also need to take care of
the _PAGE_RW bit and make sure it's cleared, otherwise even with the
_PAGE_UFFD_WP bit we can't trap it at all.
In change_pte_range() we do nothing for uffd if the PTE is a swap entry.
That can lead to data mismatch if the page that we are going to write
protect is swapped out when sending the UFFDIO_WRITEPROTECT. This patch
also applies/removes the uffd-wp bit even for the swap entries.
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Martin Cracauer <cracauer@cons.org>
Cc: Marty McFadden <mcfadden8@llnl.gov>
Cc: Maya Gokhale <gokhale2@llnl.gov>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shli@fb.com>
Link: http://lkml.kernel.org/r/20200220163112.11409-11-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
UFFD_EVENT_FORK support for uffd-wp should be already there, except that
we should clean the uffd-wp bit if uffd fork event is not enabled. Detect
that to avoid _PAGE_UFFD_WP being set even if the VMA is not being tracked
by VM_UFFD_WP. Do this for both small PTEs and huge PMDs.
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Martin Cracauer <cracauer@cons.org>
Cc: Marty McFadden <mcfadden8@llnl.gov>
Cc: Maya Gokhale <gokhale2@llnl.gov>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shli@fb.com>
Link: http://lkml.kernel.org/r/20200220163112.11409-9-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Firstly, introduce two new flags MM_CP_UFFD_WP[_RESOLVE] for
change_protection() when used with uffd-wp and make sure the two new flags
are exclusively used. Then,
- For MM_CP_UFFD_WP: apply the _PAGE_UFFD_WP bit and remove _PAGE_RW
when a range of memory is write protected by uffd
- For MM_CP_UFFD_WP_RESOLVE: remove the _PAGE_UFFD_WP bit and recover
_PAGE_RW when write protection is resolved from userspace
And use this new interface in mwriteprotect_range() to replace the old
MM_CP_DIRTY_ACCT.
Do this change for both PTEs and huge PMDs. Then we can start to identify
which PTE/PMD is write protected by general (e.g., COW or soft dirty
tracking), and which is for userfaultfd-wp.
Since we should keep the _PAGE_UFFD_WP when doing pte_modify(), add it
into _PAGE_CHG_MASK as well. Meanwhile, since we have this new bit, we
can be even more strict when detecting uffd-wp page faults in either
do_wp_page() or wp_huge_pmd().
After we're with _PAGE_UFFD_WP, a special case is when a page is both
protected by the general COW logic and also userfault-wp. Here the
userfault-wp will have higher priority and will be handled first. Only
after the uffd-wp bit is cleared on the PTE/PMD will we continue to handle
the general COW. These are the steps on what will happen with such a
page:
1. CPU accesses write protected shared page (so both protected by
general COW and uffd-wp), blocked by uffd-wp first because in
do_wp_page we'll handle uffd-wp first, so it has higher priority
than general COW.
2. Uffd service thread receives the request, do UFFDIO_WRITEPROTECT
to remove the uffd-wp bit upon the PTE/PMD. However here we
still keep the write bit cleared. Notify the blocked CPU.
3. The blocked CPU resumes the page fault process with a fault
retry, during retry it'll notice it was not with the uffd-wp bit
this time but it is still write protected by general COW, then
it'll go though the COW path in the fault handler, copy the page,
apply write bit where necessary, and retry again.
4. The CPU will be able to access this page with write bit set.
Suggested-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Martin Cracauer <cracauer@cons.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Maya Gokhale <gokhale2@llnl.gov>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Marty McFadden <mcfadden8@llnl.gov>
Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shli@fb.com>
Link: http://lkml.kernel.org/r/20200220163112.11409-8-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
change_protection() was used by either the NUMA or mprotect() code,
there's one parameter for each of the callers (dirty_accountable and
prot_numa). Further, these parameters are passed along the calls:
- change_protection_range()
- change_p4d_range()
- change_pud_range()
- change_pmd_range()
- ...
Now we introduce a flag for change_protect() and all these helpers to
replace these parameters. Then we can avoid passing multiple parameters
multiple times along the way.
More importantly, it'll greatly simplify the work if we want to introduce
any new parameters to change_protection(). In the follow up patches, a
new parameter for userfaultfd write protection will be introduced.
No functional change at all.
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Martin Cracauer <cracauer@cons.org>
Cc: Marty McFadden <mcfadden8@llnl.gov>
Cc: Maya Gokhale <gokhale2@llnl.gov>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Shaohua Li <shli@fb.com>
Link: http://lkml.kernel.org/r/20200220163112.11409-7-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are several cases write protection fault happens. It could be a
write to zero page, swaped page or userfault write protected page. When
the fault happens, there is no way to know if userfault write protect the
page before. Here we just blindly issue a userfault notification for vma
with VM_UFFD_WP regardless if app write protects it yet. Application
should be ready to handle such wp fault.
In the swapin case, always swapin as readonly. This will cause false
positive userfaults. We need to decide later if to eliminate them with a
flag like soft-dirty in the swap entry (see _PAGE_SWP_SOFT_DIRTY).
hugetlbfs wouldn't need to worry about swapouts but and tmpfs would be
handled by a swap entry bit like anonymous memory.
The main problem with no easy solution to eliminate the false positives,
will be if/when userfaultfd is extended to real filesystem pagecache.
When the pagecache is freed by reclaim we can't leave the radix tree
pinned if the inode and in turn the radix tree is reclaimed as well.
The estimation is that full accuracy and lack of false positives could be
easily provided only to anonymous memory (as long as there's no fork or as
long as MADV_DONTFORK is used on the userfaultfd anonymous range) tmpfs
and hugetlbfs, it's most certainly worth to achieve it but in a later
incremental patch.
[peterx@redhat.com: don't conditionally drop FAULT_FLAG_WRITE in do_swap_page]
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Cc: Shaohua Li <shli@fb.com>
Cc: Bobby Powers <bobbypowers@gmail.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Denis Plotnikov <dplotnikov@virtuozzo.com>
Cc: "Dr . David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Martin Cracauer <cracauer@cons.org>
Cc: Marty McFadden <mcfadden8@llnl.gov>
Cc: Maya Gokhale <gokhale2@llnl.gov>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Rik van Riel <riel@redhat.com>
Link: http://lkml.kernel.org/r/20200220163112.11409-3-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In order to keep ourselves from reporting pages that are just going to be
reused again in the case of heavy churn we can put a limit on how many
total pages we will process per pass. Doing this will allow the worker
thread to go into idle much more quickly so that we avoid competing with
other threads that might be allocating or freeing pages.
The logic added here will limit the worker thread to no more than one
sixteenth of the total free pages in a given area per list. Once that
limit is reached it will update the state so that at the end of the pass
we will reschedule the worker to try again in 2 seconds when the memory
churn has hopefully settled down.
Again this optimization doesn't show much of a benefit in the standard
case as the memory churn is minmal. However with page allocator shuffling
enabled the gain is quite noticeable. Below are the results with a THP
enabled version of the will-it-scale page_fault1 test showing the
improvement in iterations for 16 processes or threads.
Without:
tasks processes processes_idle threads threads_idle
16 8283274.75 0.17 5594261.00 38.15
With:
tasks processes processes_idle threads threads_idle
16 8767010.50 0.21 5791312.75 36.98
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pagupta@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Wang <wei.w.wang@intel.com>
Cc: Yang Zhang <yang.zhang.wz@gmail.com>
Cc: wei qi <weiqi4@huawei.com>
Link: http://lkml.kernel.org/r/20200211224719.29318.72113.stgit@localhost.localdomain
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Rather than walking over the same pages again and again to get to the
pages that have yet to be reported we can save ourselves a significant
amount of time by simply rotating the list so that when we have a full
list of reported pages the head of the list is pointing to the next
non-reported page. Doing this should save us some significant time when
processing each free list.
This doesn't gain us much in the standard case as all of the non-reported
pages should be near the top of the list already. However in the case of
page shuffling this results in a noticeable improvement. Below are the
will-it-scale page_fault1 w/ THP numbers for 16 tasks with and without
this patch.
Without:
tasks processes processes_idle threads threads_idle
16 8093776.25 0.17 5393242.00 38.20
With:
tasks processes processes_idle threads threads_idle
16 8283274.75 0.17 5594261.00 38.15
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pagupta@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Wang <wei.w.wang@intel.com>
Cc: Yang Zhang <yang.zhang.wz@gmail.com>
Cc: wei qi <weiqi4@huawei.com>
Link: http://lkml.kernel.org/r/20200211224708.29318.16862.stgit@localhost.localdomain
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In order to pave the way for free page reporting in virtualized
environments we will need a way to get pages out of the free lists and
identify those pages after they have been returned. To accomplish this,
this patch adds the concept of a Reported Buddy, which is essentially
meant to just be the Uptodate flag used in conjunction with the Buddy page
type.
To prevent the reported pages from leaking outside of the buddy lists I
added a check to clear the PageReported bit in the del_page_from_free_list
function. As a result any reported page that is split, merged, or
allocated will have the flag cleared prior to the PageBuddy value being
cleared.
The process for reporting pages is fairly simple. Once we free a page
that meets the minimum order for page reporting we will schedule a worker
thread to start 2s or more in the future. That worker thread will begin
working from the lowest supported page reporting order up to MAX_ORDER - 1
pulling unreported pages from the free list and storing them in the
scatterlist.
When processing each individual free list it is necessary for the worker
thread to release the zone lock when it needs to stop and report the full
scatterlist of pages. To reduce the work of the next iteration the worker
thread will rotate the free list so that the first unreported page in the
free list becomes the first entry in the list.
It will then call a reporting function providing information on how many
entries are in the scatterlist. Once the function completes it will
return the pages to the free area from which they were allocated and start
over pulling more pages from the free areas until there are no longer
enough pages to report on to keep the worker busy, or we have processed as
many pages as were contained in the free area when we started processing
the list.
The worker thread will work in a round-robin fashion making its way though
each zone requesting reporting, and through each reportable free list
within that zone. Once all free areas within the zone have been processed
it will check to see if there have been any requests for reporting while
it was processing. If so it will reschedule the worker thread to start up
again in roughly 2s and exit.
Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pankaj Gupta <pagupta@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Wang <wei.w.wang@intel.com>
Cc: Yang Zhang <yang.zhang.wz@gmail.com>
Cc: wei qi <weiqi4@huawei.com>
Link: http://lkml.kernel.org/r/20200211224635.29318.19750.stgit@localhost.localdomain
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
