08 Apr, 2020
2 commits
-
If CONFIG_DEVICE_PRIVATE is defined, but neither CONFIG_MEMORY_FAILURE nor
CONFIG_MIGRATION, then non_swap_entry() will return 0, meaning that the
condition (non_swap_entry(entry) && is_device_private_entry(entry)) in
zap_pte_range() will never be true even if the entry is a device private
one.Equally any other code depending on non_swap_entry() will not function as
expected.I originally spotted this just by looking at the code, I haven't actually
observed any problems.Looking a bit more closely it appears that actually this situation
(currently at least) cannot occur:DEVICE_PRIVATE depends on ZONE_DEVICE
ZONE_DEVICE depends on MEMORY_HOTREMOVE
MEMORY_HOTREMOVE depends on MIGRATIONFixes: 5042db43cc26 ("mm/ZONE_DEVICE: new type of ZONE_DEVICE for unaddressable memory")
Signed-off-by: Steven Price
Signed-off-by: Andrew Morton
Cc: Jérôme Glisse
Cc: Arnd Bergmann
Cc: Dan Williams
Cc: John Hubbard
Link: http://lkml.kernel.org/r/20200305130550.22693-1-steven.price@arm.com
Signed-off-by: Linus Torvalds -
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
Signed-off-by: Andrew Morton
Cc: Andrea Arcangeli
Cc: Bobby Powers
Cc: Brian Geffon
Cc: David Hildenbrand
Cc: Denis Plotnikov
Cc: "Dr . David Alan Gilbert"
Cc: Hugh Dickins
Cc: Jerome Glisse
Cc: Johannes Weiner
Cc: "Kirill A . Shutemov"
Cc: Martin Cracauer
Cc: Marty McFadden
Cc: Maya Gokhale
Cc: Mel Gorman
Cc: Mike Kravetz
Cc: Mike Rapoport
Cc: Pavel Emelyanov
Cc: Rik van Riel
Cc: Shaohua Li
Link: http://lkml.kernel.org/r/20200220163112.11409-11-peterx@redhat.com
Signed-off-by: Linus Torvalds
17 Jul, 2019
1 commit
-
The whole header file deals with swap entries and PTEs, none of which
can exist for nommu builds. The current nommu ports have lots of stubs
to allow the inline functions in swapops.h to compile, but as none of
this functionality is actually used there is no point in even providing
it. This way we don't have to provide the stubs for the upcoming RISC-V
nommu port, and can eventually remove it from the existing ports.Link: http://lkml.kernel.org/r/20190703122359.18200-4-hch@lst.de
Signed-off-by: Christoph Hellwig
Cc: Vladimir Murzin
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
03 Jul, 2019
1 commit
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This replaces the hacky ->fault callback, which is currently directly
called from common code through a hmm specific data structure as an
exercise in layering violations.Signed-off-by: Christoph Hellwig
Reviewed-by: Ralph Campbell
Reviewed-by: Jason Gunthorpe
Reviewed-by: Dan Williams
Tested-by: Dan Williams
Signed-off-by: Jason Gunthorpe
30 Sep, 2018
1 commit
-
Introduce xarray value entries and tagged pointers to replace radix
tree exceptional entries. This is a slight change in encoding to allow
the use of an extra bit (we can now store BITS_PER_LONG - 1 bits in a
value entry). It is also a change in emphasis; exceptional entries are
intimidating and different. As the comment explains, you can choose
to store values or pointers in the xarray and they are both first-class
citizens.Signed-off-by: Matthew Wilcox
Reviewed-by: Josef Bacik
24 Aug, 2018
2 commits
-
Use new return type vm_fault_t for fault handler. For now, this is just
documenting that the function returns a VM_FAULT value rather than an
errno. Once all instances are converted, vm_fault_t will become a
distinct type.Ref-> commit 1c8f422059ae ("mm: change return type to vm_fault_t")
The aim is to change the return type of finish_fault() and
handle_mm_fault() to vm_fault_t type. As part of that clean up return
type of all other recursively called functions have been changed to
vm_fault_t type.The places from where handle_mm_fault() is getting invoked will be
change to vm_fault_t type but in a separate patch.vmf_error() is the newly introduce inline function in 4.17-rc6.
[akpm@linux-foundation.org: don't shadow outer local `ret' in __do_huge_pmd_anonymous_page()]
Link: http://lkml.kernel.org/r/20180604171727.GA20279@jordon-HP-15-Notebook-PC
Signed-off-by: Souptick Joarder
Reviewed-by: Matthew Wilcox
Reviewed-by: Andrew Morton
Cc: Matthew Wilcox
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
A process can be killed with SIGBUS(BUS_MCEERR_AR) when it tries to
allocate a page that was just freed on the way of soft-offline. This is
undesirable because soft-offline (which is about corrected error) is
less aggressive than hard-offline (which is about uncorrected error),
and we can make soft-offline fail and keep using the page for good
reason like "system is busy."Two main changes of this patch are:
- setting migrate type of the target page to MIGRATE_ISOLATE. As done
in free_unref_page_commit(), this makes kernel bypass pcplist when
freeing the page. So we can assume that the page is in freelist just
after put_page() returns,- setting PG_hwpoison on free page under zone->lock which protects
freelists, so this allows us to avoid setting PG_hwpoison on a page
that is decided to be allocated soon.[akpm@linux-foundation.org: tweak set_hwpoison_free_buddy_page() comment]
Link: http://lkml.kernel.org/r/1531452366-11661-3-git-send-email-n-horiguchi@ah.jp.nec.com
Signed-off-by: Naoya Horiguchi
Reported-by: Xishi Qiu
Tested-by: Mike Kravetz
Cc: Michal Hocko
Cc:
Cc: Mike Kravetz
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
22 Jan, 2018
1 commit
-
Tetsuo reported random crashes under memory pressure on 32-bit x86
system and tracked down to change that introduced
page_vma_mapped_walk().The root cause of the issue is the faulty pointer math in check_pte().
As ->pte may point to an arbitrary page we have to check that they are
belong to the section before doing math. Otherwise it may lead to weird
results.It wasn't noticed until now as mem_map[] is virtually contiguous on
flatmem or vmemmap sparsemem. Pointer arithmetic just works against all
'struct page' pointers. But with classic sparsemem, it doesn't because
each section memap is allocated separately and so consecutive pfns
crossing two sections might have struct pages at completely unrelated
addresses.Let's restructure code a bit and replace pointer arithmetic with
operations on pfns.Signed-off-by: Kirill A. Shutemov
Reported-and-tested-by: Tetsuo Handa
Acked-by: Michal Hocko
Fixes: ace71a19cec5 ("mm: introduce page_vma_mapped_walk()")
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds
02 Nov, 2017
1 commit
-
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.By default all files without license information are under the default
license of the kernel, which is GPL version 2.Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if
Reviewed-by: Philippe Ombredanne
Reviewed-by: Thomas Gleixner
Signed-off-by: Greg Kroah-Hartman
09 Sep, 2017
3 commits
-
HMM (heterogeneous memory management) need struct page to support
migration from system main memory to device memory. Reasons for HMM and
migration to device memory is explained with HMM core patch.This patch deals with device memory that is un-addressable memory (ie CPU
can not access it). Hence we do not want those struct page to be manage
like regular memory. That is why we extend ZONE_DEVICE to support
different types of memory.A persistent memory type is define for existing user of ZONE_DEVICE and a
new device un-addressable type is added for the un-addressable memory
type. There is a clear separation between what is expected from each
memory type and existing user of ZONE_DEVICE are un-affected by new
requirement and new use of the un-addressable type. All specific code
path are protect with test against the memory type.Because memory is un-addressable we use a new special swap type for when a
page is migrated to device memory (this reduces the number of maximum swap
file).The main two additions beside memory type to ZONE_DEVICE is two callbacks.
First one, page_free() is call whenever page refcount reach 1 (which
means the page is free as ZONE_DEVICE page never reach a refcount of 0).
This allow device driver to manage its memory and associated struct page.The second callback page_fault() happens when there is a CPU access to an
address that is back by a device page (which are un-addressable by the
CPU). This callback is responsible to migrate the page back to system
main memory. Device driver can not block migration back to system memory,
HMM make sure that such page can not be pin into device memory.If device is in some error condition and can not migrate memory back then
a CPU page fault to device memory should end with SIGBUS.[arnd@arndb.de: fix warning]
Link: http://lkml.kernel.org/r/20170823133213.712917-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/20170817000548.32038-8-jglisse@redhat.com
Signed-off-by: Jérôme Glisse
Signed-off-by: Arnd Bergmann
Acked-by: Dan Williams
Cc: Ross Zwisler
Cc: Aneesh Kumar
Cc: Balbir Singh
Cc: Benjamin Herrenschmidt
Cc: David Nellans
Cc: Evgeny Baskakov
Cc: Johannes Weiner
Cc: John Hubbard
Cc: Kirill A. Shutemov
Cc: Mark Hairgrove
Cc: Michal Hocko
Cc: Paul E. McKenney
Cc: Sherry Cheung
Cc: Subhash Gutti
Cc: Vladimir Davydov
Cc: Bob Liu
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Soft dirty bit is designed to keep tracked over page migration. This
patch makes it work in the same manner for thp migration too.Signed-off-by: Naoya Horiguchi
Signed-off-by: Zi Yan
Cc: "H. Peter Anvin"
Cc: Anshuman Khandual
Cc: Dave Hansen
Cc: David Nellans
Cc: Ingo Molnar
Cc: Kirill A. Shutemov
Cc: Mel Gorman
Cc: Minchan Kim
Cc: Thomas Gleixner
Cc: Vlastimil Babka
Cc: Andrea Arcangeli
Cc: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add thp migration's core code, including conversions between a PMD entry
and a swap entry, setting PMD migration entry, removing PMD migration
entry, and waiting on PMD migration entries.This patch makes it possible to support thp migration. If you fail to
allocate a destination page as a thp, you just split the source thp as
we do now, and then enter the normal page migration. If you succeed to
allocate destination thp, you enter thp migration. Subsequent patches
actually enable thp migration for each caller of page migration by
allowing its get_new_page() callback to allocate thps.[zi.yan@cs.rutgers.edu: fix gcc-4.9.0 -Wmissing-braces warning]
Link: http://lkml.kernel.org/r/A0ABA698-7486-46C3-B209-E95A9048B22C@cs.rutgers.edu
[akpm@linux-foundation.org: fix x86_64 allnoconfig warning]
Signed-off-by: Zi Yan
Acked-by: Kirill A. Shutemov
Cc: "H. Peter Anvin"
Cc: Anshuman Khandual
Cc: Dave Hansen
Cc: David Nellans
Cc: Ingo Molnar
Cc: Mel Gorman
Cc: Minchan Kim
Cc: Naoya Horiguchi
Cc: Thomas Gleixner
Cc: Vlastimil Babka
Cc: Andrea Arcangeli
Cc: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
11 Jul, 2017
1 commit
-
We'd like to narrow down the error region in memory error on hugetlb
pages. However, currently we set PageHWPoison flags on all subpages in
the error hugepage and add # of subpages to num_hwpoison_pages, which
doesn't fit our purpose.So this patch changes the behavior and we only set PageHWPoison on the
head page then increase num_hwpoison_pages only by 1. This is a
preparation for narrow-down part which comes in later patches.Link: http://lkml.kernel.org/r/1496305019-5493-4-git-send-email-n-horiguchi@ah.jp.nec.com
Signed-off-by: Naoya Horiguchi
Cc: Michal Hocko
Cc: "Aneesh Kumar K.V"
Cc: Anshuman Khandual
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
09 Sep, 2015
2 commits
-
Wanpeng Li reported a race between soft_offline_page() and
unpoison_memory(), which causes the following kernel panic:BUG: Bad page state in process bash pfn:97000
page:ffffea00025c0000 count:0 mapcount:1 mapping: (null) index:0x7f4fdbe00
flags: 0x1fffff80080048(uptodate|active|swapbacked)
page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set
bad because of flags:
flags: 0x40(active)
Modules linked in: snd_hda_codec_hdmi i915 rpcsec_gss_krb5 nfsv4 dns_resolver bnep rfcomm nfsd bluetooth auth_rpcgss nfs_acl nfs rfkill lockd grace sunrpc i2c_algo_bit drm_kms_helper snd_hda_codec_realtek snd_hda_codec_generic drm snd_hda_intel fscache snd_hda_codec x86_pkg_temp_thermal coretemp kvm_intel snd_hda_core snd_hwdep kvm snd_pcm snd_seq_dummy snd_seq_oss crct10dif_pclmul snd_seq_midi crc32_pclmul snd_seq_midi_event ghash_clmulni_intel snd_rawmidi aesni_intel lrw gf128mul snd_seq glue_helper ablk_helper snd_seq_device cryptd fuse snd_timer dcdbas serio_raw mei_me parport_pc snd mei ppdev i2c_core video lp soundcore parport lpc_ich shpchp mfd_core ext4 mbcache jbd2 sd_mod e1000e ahci ptp libahci crc32c_intel libata pps_core
CPU: 3 PID: 2211 Comm: bash Not tainted 4.2.0-rc5-mm1+ #45
Hardware name: Dell Inc. OptiPlex 7020/0F5C5X, BIOS A03 01/08/2015
Call Trace:
dump_stack+0x48/0x5c
bad_page+0xe6/0x140
free_pages_prepare+0x2f9/0x320
? uncharge_list+0xdd/0x100
free_hot_cold_page+0x40/0x170
__put_single_page+0x20/0x30
put_page+0x25/0x40
unmap_and_move+0x1a6/0x1f0
migrate_pages+0x100/0x1d0
? kill_procs+0x100/0x100
? unlock_page+0x6f/0x90
__soft_offline_page+0x127/0x2a0
soft_offline_page+0xa6/0x200This race is explained like below:
CPU0 CPU1
soft_offline_page
__soft_offline_page
TestSetPageHWPoison
unpoison_memory
PageHWPoison check (true)
TestClearPageHWPoison
put_page -> release refcount held by get_hwpoison_page in unpoison_memory
put_page -> release refcount held by isolate_lru_page in __soft_offline_page
migrate_pagesThe second put_page() releases refcount held by isolate_lru_page() which
will lead to unmap_and_move() releases the last refcount of page and w/
mapcount still 1 since try_to_unmap() is not called if there is only one
user map the page. Anyway, the page refcount and mapcount will still
mess if the page is mapped by multiple users.This race was introduced by commit 4491f71260 ("mm/memory-failure: set
PageHWPoison before migrate_pages()"), which focuses on preventing the
reuse of successfully migrated page. Before this commit we prevent the
reuse by changing the migratetype to MIGRATE_ISOLATE during soft
offlining, which has the following problems, so simply reverting the
commit is not a best option:1) it doesn't eliminate the reuse completely, because
set_migratetype_isolate() can fail to set MIGRATE_ISOLATE to the
target page if the pageblock of the page contains one or more
unmovable pages (i.e. has_unmovable_pages() returns true).2) the original code changes migratetype to MIGRATE_ISOLATE
forcibly, and sets it to MIGRATE_MOVABLE forcibly after soft offline,
regardless of the original migratetype state, which could impact
other subsystems like memory hotplug or compaction.This patch moves PageSetHWPoison just after put_page() in
unmap_and_move(), which closes up the reported race window and minimizes
another race window b/w SetPageHWPoison and reallocation (which causes
the reuse of soft-offlined page.) The latter race window still exists
but it's acceptable, because it's rare and effectively the same as
ordinary "containment failure" case even if it happens, so keep the
window open is acceptable.Fixes: 4491f71260 ("mm/memory-failure: set PageHWPoison before migrate_pages()")
Signed-off-by: Wanpeng Li
Signed-off-by: Naoya Horiguchi
Reported-by: Wanpeng Li
Tested-by: Wanpeng Li
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
num_poisoned_pages counter will be changed outside mm/memory-failure.c
by a subsequent patch, so this patch prepares wrappers to manipulate it.Signed-off-by: Naoya Horiguchi
Tested-by: Wanpeng Li
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
13 Feb, 2015
1 commit
-
This patch removes the NUMA PTE bits and associated helpers. As a
side-effect it increases the maximum possible swap space on x86-64.One potential source of problems is races between the marking of PTEs
PROT_NONE, NUMA hinting faults and migration. It must be guaranteed that
a PTE being protected is not faulted in parallel, seen as a pte_none and
corrupting memory. The base case is safe but transhuge has problems in
the past due to an different migration mechanism and a dependance on page
lock to serialise migrations and warrants a closer look.task_work hinting update parallel fault
------------------------ --------------
change_pmd_range
change_huge_pmd
__pmd_trans_huge_lock
pmdp_get_and_clear
__handle_mm_fault
pmd_none
do_huge_pmd_anonymous_page
read? pmd_lock blocks until hinting complete, fail !pmd_none test
write? __do_huge_pmd_anonymous_page acquires pmd_lock, checks pmd_none
pmd_modify
set_pmd_attask_work hinting update parallel migration
------------------------ ------------------
change_pmd_range
change_huge_pmd
__pmd_trans_huge_lock
pmdp_get_and_clear
__handle_mm_fault
do_huge_pmd_numa_page
migrate_misplaced_transhuge_page
pmd_lock waits for updates to complete, recheck pmd_same
pmd_modify
set_pmd_atBoth of those are safe and the case where a transhuge page is inserted
during a protection update is unchanged. The case where two processes try
migrating at the same time is unchanged by this series so should still be
ok. I could not find a case where we are accidentally depending on the
PTE not being cleared and flushed. If one is missed, it'll manifest as
corruption problems that start triggering shortly after this series is
merged and only happen when NUMA balancing is enabled.Signed-off-by: Mel Gorman
Tested-by: Sasha Levin
Cc: Aneesh Kumar K.V
Cc: Benjamin Herrenschmidt
Cc: Dave Jones
Cc: Hugh Dickins
Cc: Ingo Molnar
Cc: Kirill Shutemov
Cc: Linus Torvalds
Cc: Paul Mackerras
Cc: Rik van Riel
Cc: Mark Brown
Cc: Stephen Rothwell
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
12 Feb, 2015
1 commit
-
We have a race condition between move_pages() and freeing hugepages, where
move_pages() calls follow_page(FOLL_GET) for hugepages internally and
tries to get its refcount without preventing concurrent freeing. This
race crashes the kernel, so this patch fixes it by moving FOLL_GET code
for hugepages into follow_huge_pmd() with taking the page table lock.This patch intentionally removes page==NULL check after pte_page.
This is justified because pte_page() never returns NULL for any
architectures or configurations.This patch changes the behavior of follow_huge_pmd() for tail pages and
then tail pages can be pinned/returned. So the caller must be changed to
properly handle the returned tail pages.We could have a choice to add the similar locking to
follow_huge_(addr|pud) for consistency, but it's not necessary because
currently these functions don't support FOLL_GET flag, so let's leave it
for future development.Here is the reproducer:
$ cat movepages.c
#include
#include
#include#define ADDR_INPUT 0x700000000000UL
#define HPS 0x200000
#define PS 0x1000int main(int argc, char *argv[]) {
int i;
int nr_hp = strtol(argv[1], NULL, 0);
int nr_p = nr_hp * HPS / PS;
int ret;
void **addrs;
int *status;
int *nodes;
pid_t pid;pid = strtol(argv[2], NULL, 0);
addrs = malloc(sizeof(char *) * nr_p + 1);
status = malloc(sizeof(char *) * nr_p + 1);
nodes = malloc(sizeof(char *) * nr_p + 1);while (1) {
for (i = 0; i < nr_p; i++) {
addrs[i] = (void *)ADDR_INPUT + i * PS;
nodes[i] = 1;
status[i] = 0;
}
ret = numa_move_pages(pid, nr_p, addrs, nodes, status,
MPOL_MF_MOVE_ALL);
if (ret == -1)
err("move_pages");for (i = 0; i < nr_p; i++) {
addrs[i] = (void *)ADDR_INPUT + i * PS;
nodes[i] = 0;
status[i] = 0;
}
ret = numa_move_pages(pid, nr_p, addrs, nodes, status,
MPOL_MF_MOVE_ALL);
if (ret == -1)
err("move_pages");
}
return 0;
}$ cat hugepage.c
#include
#include
#include#define ADDR_INPUT 0x700000000000UL
#define HPS 0x200000int main(int argc, char *argv[]) {
int nr_hp = strtol(argv[1], NULL, 0);
char *p;while (1) {
p = mmap((void *)ADDR_INPUT, nr_hp * HPS, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0);
if (p != (void *)ADDR_INPUT) {
perror("mmap");
break;
}
memset(p, 0, nr_hp * HPS);
munmap(p, nr_hp * HPS);
}
}$ sysctl vm.nr_hugepages=40
$ ./hugepage 10 &
$ ./movepages 10 $(pgrep -f hugepage)Fixes: e632a938d914 ("mm: migrate: add hugepage migration code to move_pages()")
Signed-off-by: Naoya Horiguchi
Reported-by: Hugh Dickins
Cc: James Hogan
Cc: David Rientjes
Cc: Mel Gorman
Cc: Johannes Weiner
Cc: Michal Hocko
Cc: Rik van Riel
Cc: Andrea Arcangeli
Cc: Luiz Capitulino
Cc: Nishanth Aravamudan
Cc: Lee Schermerhorn
Cc: Steve Capper
Cc: [3.12+]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
11 Feb, 2015
1 commit
-
One bit in ->vm_flags is unused now!
Signed-off-by: Kirill A. Shutemov
Cc: Dan Carpenter
Cc: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
05 Jun, 2014
1 commit
-
_PAGE_NUMA is currently an alias of _PROT_PROTNONE to trap NUMA hinting
faults on x86. Care is taken such that _PAGE_NUMA is used only in
situations where the VMA flags distinguish between NUMA hinting faults
and prot_none faults. This decision was x86-specific and conceptually
it is difficult requiring special casing to distinguish between PROTNONE
and NUMA ptes based on context.Fundamentally, we only need the _PAGE_NUMA bit to tell the difference
between an entry that is really unmapped and a page that is protected
for NUMA hinting faults as if the PTE is not present then a fault will
be trapped.Swap PTEs on x86-64 use the bits after _PAGE_GLOBAL for the offset.
This patch shrinks the maximum possible swap size and uses the bit to
uniquely distinguish between NUMA hinting ptes and swap ptes.Signed-off-by: Mel Gorman
Cc: David Vrabel
Cc: Ingo Molnar
Cc: Peter Anvin
Cc: Fengguang Wu
Cc: Linus Torvalds
Cc: Steven Noonan
Cc: Rik van Riel
Cc: Peter Zijlstra
Cc: Andrea Arcangeli
Cc: Dave Hansen
Cc: Srikar Dronamraju
Cc: Cyrill Gorcunov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
15 Nov, 2013
1 commit
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Hugetlb supports multiple page sizes. We use split lock only for PMD
level, but not for PUD.[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Naoya Horiguchi
Signed-off-by: Kirill A. Shutemov
Tested-by: Alex Thorlton
Cc: Ingo Molnar
Cc: "Eric W . Biederman"
Cc: "Paul E . McKenney"
Cc: Al Viro
Cc: Andi Kleen
Cc: Andrea Arcangeli
Cc: Dave Hansen
Cc: Dave Jones
Cc: David Howells
Cc: Frederic Weisbecker
Cc: Johannes Weiner
Cc: Kees Cook
Cc: Mel Gorman
Cc: Michael Kerrisk
Cc: Oleg Nesterov
Cc: Peter Zijlstra
Cc: Rik van Riel
Cc: Robin Holt
Cc: Sedat Dilek
Cc: Srikar Dronamraju
Cc: Thomas Gleixner
Cc: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
14 Aug, 2013
1 commit
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Andy Lutomirski reported that if a page with _PAGE_SOFT_DIRTY bit set
get swapped out, the bit is getting lost and no longer available when
pte read back.To resolve this we introduce _PTE_SWP_SOFT_DIRTY bit which is saved in
pte entry for the page being swapped out. When such page is to be read
back from a swap cache we check for bit presence and if it's there we
clear it and restore the former _PAGE_SOFT_DIRTY bit back.One of the problem was to find a place in pte entry where we can save
the _PTE_SWP_SOFT_DIRTY bit while page is in swap. The _PAGE_PSE was
chosen for that, it doesn't intersect with swap entry format stored in
pte.Reported-by: Andy Lutomirski
Signed-off-by: Cyrill Gorcunov
Acked-by: Pavel Emelyanov
Cc: Matt Mackall
Cc: Xiao Guangrong
Cc: Marcelo Tosatti
Cc: KOSAKI Motohiro
Cc: Stephen Rothwell
Cc: Peter Zijlstra
Cc: "Aneesh Kumar K.V"
Reviewed-by: Minchan Kim
Reviewed-by: Wanpeng Li
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
13 Jun, 2013
1 commit
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When we have a page fault for the address which is backed by a hugepage
under migration, the kernel can't wait correctly and do busy looping on
hugepage fault until the migration finishes. As a result, users who try
to kick hugepage migration (via soft offlining, for example) occasionally
experience long delay or soft lockup.This is because pte_offset_map_lock() can't get a correct migration entry
or a correct page table lock for hugepage. This patch introduces
migration_entry_wait_huge() to solve this.Signed-off-by: Naoya Horiguchi
Reviewed-by: Rik van Riel
Reviewed-by: Wanpeng Li
Reviewed-by: Michal Hocko
Cc: Mel Gorman
Cc: Andi Kleen
Cc: KOSAKI Motohiro
Cc: [2.6.35+]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
16 Jun, 2012
1 commit
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Minchan Kim reports that when a system has many swap areas, and tmpfs
swaps out to the ninth or more, shmem_getpage_gfp()'s attempts to read
back the page cannot locate it, and the read fails with -ENOMEM.Whoops. Yes, I blindly followed read_swap_header()'s pte_to_swp_entry(
swp_entry_to_pte()) technique for determining maximum usable swap
offset, without stopping to realize that that actually depends upon the
pte swap encoding shifting swap offset to the higher bits and truncating
it there. Whereas our radix_tree swap encoding leaves offset in the
lower bits: it's swap "type" (that is, index of swap area) that was
truncated.Fix it by reducing the SWP_TYPE_SHIFT() in swapops.h, and removing the
broken radix_to_swp_entry(swp_to_radix_entry()) from read_swap_header().This does not reduce the usable size of a swap area any further, it
leaves it as claimed when making the original commit: no change from 3.0
on x86_64, nor on i386 without PAE; but 3.0's 512GB is reduced to 128GB
per swapfile on i386 with PAE. It's not a change I would have risked
five years ago, but with x86_64 supported for ten years, I believe it's
appropriate now.Hmm, and what if some architecture implements its swap pte with offset
encoded below type? That would equally break the maximum usable swap
offset check. Happily, they all follow the same tradition of encoding
offset above type, but I'll prepare a check on that for next.Reported-and-Reviewed-and-Tested-by: Minchan Kim
Signed-off-by: Hugh Dickins
Cc: stable@vger.kernel.org [3.1, 3.2, 3.3, 3.4]
Signed-off-by: Linus Torvalds
05 Mar, 2012
1 commit
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If a header file is making use of BUG, BUG_ON, BUILD_BUG_ON, or any
other BUG variant in a static inline (i.e. not in a #define) then
that header really should be including and not just
expecting it to be implicitly present.We can make this change risk-free, since if the files using these
headers didn't have exposure to linux/bug.h already, they would have
been causing compile failures/warnings.Signed-off-by: Paul Gortmaker
04 Aug, 2011
1 commit
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If swap entries are to be stored along with struct page pointers in a
radix tree, they need to be distinguished as exceptional entries.Most of the handling of swap entries in radix tree will be contained in
shmem.c, but a few functions in filemap.c's common code need to check
for their appearance: find_get_page(), find_lock_page(),
find_get_pages() and find_get_pages_contig().So as not to slow their fast paths, tuck those checks inside the
existing checks for unlikely radix_tree_deref_slot(); except for
find_lock_page(), where it is an added test. And make it a BUG in
find_get_pages_tag(), which is not applied to tmpfs files.A part of the reason for eliminating shmem_readpage() earlier, was to
minimize the places where common code would need to allow for swap
entries.The swp_entry_t known to swapfile.c must be massaged into a slightly
different form when stored in the radix tree, just as it gets massaged
into a pte_t when stored in page tables.In an i386 kernel this limits its information (type and page offset) to
30 bits: given 32 "types" of swapfile and 4kB pagesize, that's a maximum
swapfile size of 128GB. Which is less than the 512GB we previously
allowed with X86_PAE (where the swap entry can occupy the entire upper
32 bits of a pte_t), but not a new limitation on 32-bit without PAE; and
there's not a new limitation on 64-bit (where swap filesize is already
limited to 16TB by a 32-bit page offset). Thirty areas of 128GB is
probably still enough swap for a 64GB 32-bit machine.Provide swp_to_radix_entry() and radix_to_swp_entry() conversions, and
enforce filesize limit in read_swap_header(), just as for ptes.Signed-off-by: Hugh Dickins
Acked-by: Rik van Riel
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
16 Sep, 2009
1 commit
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Memory migration uses special swap entry types to trigger special actions on
page faults. Extend this mechanism to also support poisoned swap entries, to
trigger poison handling on page faults. This allows follow-on patches to
prevent processes from faulting in poisoned pages again.v2: Fix overflow in MAX_SWAPFILES (Fengguang Wu)
v3: Better overflow fix (Hidehiro Kawai)Signed-off-by: Andi Kleen
10 Feb, 2008
1 commit
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CC mm/vmscan.o
In file included from
/home/bunk/linux/kernel-2.6/git/linux-2.6/mm/vmscan.c:44:
/home/bunk/linux/kernel-2.6/git/linux-2.6/include/linux/swapops.h: In function 'is_swap_pte':
/home/bunk/linux/kernel-2.6/git/linux-2.6/include/linux/swapops.h:48: error: implicit declaration of function 'pte_none'
/home/bunk/linux/kernel-2.6/git/linux-2.6/include/linux/swapops.h:48: error: implicit declaration of function 'pte_present'Does it ever make sense to ask "is this pte a swap entry?" on a machine
with no MMU? Presumably this also means it has no ptes too, right? In
which case, it's better to comment the whole function out. Then when
someone tries to ask the above meaningless question, they get a compile
error rather than a meaningless answer.Signed-off-by: Matt Mackall
Cc: Mike Frysinger
Reported-by: Adrian Bunk
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
06 Feb, 2008
1 commit
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Move is_swap_pte helper function to swapops.h for use by pagemap code
Signed-off-by: Matt Mackall
Cc: Dave Hansen
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
21 Feb, 2007
1 commit
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allnoconfig:
mm/mincore.c: In function 'do_mincore':
mm/mincore.c:122: warning: unused variable 'entry'Yet another entry in the why-macros-are-wrong encyclopedia.
Cc: Christoph Lameter
Cc: Nick Piggin
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
23 Jun, 2006
1 commit
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Implement read/write migration ptes
We take the upper two swapfiles for the two types of migration ptes and define
a series of macros in swapops.h.The VM is modified to handle the migration entries. migration entries can
only be encountered when the page they are pointing to is locked. This limits
the number of places one has to fix. We also check in copy_pte_range and in
mprotect_pte_range() for migration ptes.We check for migration ptes in do_swap_cache and call a function that will
then wait on the page lock. This allows us to effectively stop all accesses
to apge.Migration entries are created by try_to_unmap if called for migration and
removed by local functions in migrate.cFrom: Hugh Dickins
Several times while testing swapless page migration (I've no NUMA, just
hacking it up to migrate recklessly while running load), I've hit the
BUG_ON(!PageLocked(p)) in migration_entry_to_page.This comes from an orphaned migration entry, unrelated to the current
correctly locked migration, but hit by remove_anon_migration_ptes as it
checks an address in each vma of the anon_vma list.Such an orphan may be left behind if an earlier migration raced with fork:
copy_one_pte can duplicate a migration entry from parent to child, after
remove_anon_migration_ptes has checked the child vma, but before it has
removed it from the parent vma. (If the process were later to fault on this
orphaned entry, it would hit the same BUG from migration_entry_wait.)This could be fixed by locking anon_vma in copy_one_pte, but we'd rather
not. There's no such problem with file pages, because vma_prio_tree_add
adds child vma after parent vma, and the page table locking at each end is
enough to serialize. Follow that example with anon_vma: add new vmas to the
tail instead of the head.(There's no corresponding problem when inserting migration entries,
because a missed pte will leave the page count and mapcount high, which is
allowed for. And there's no corresponding problem when migrating via swap,
because a leftover swap entry will be correctly faulted. But the swapless
method has no refcounting of its entries.)From: Ingo Molnar
pte_unmap_unlock() takes the pte pointer as an argument.
From: Hugh Dickins
Several times while testing swapless page migration, gcc has tried to exec
a pointer instead of a string: smells like COW mappings are not being
properly write-protected on fork.The protection in copy_one_pte looks very convincing, until at last you
realize that the second arg to make_migration_entry is a boolean "write",
and SWP_MIGRATION_READ is 30.Anyway, it's better done like in change_pte_range, using
is_write_migration_entry and make_migration_entry_read.From: Hugh Dickins
Remove unnecessary obfuscation from sys_swapon's range check on swap type,
which blew up causing memory corruption once swapless migration made
MAX_SWAPFILES no longer 2 ^ MAX_SWAPFILES_SHIFT.Signed-off-by: Hugh Dickins
Acked-by: Martin Schwidefsky
Signed-off-by: Hugh Dickins
Signed-off-by: Christoph Lameter
Signed-off-by: Ingo Molnar
From: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
05 Sep, 2005
1 commit
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smp_entry_t -> swap_entry_t
Signed-off-by: Paolo 'Blaisorblade' Giarrusso
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
17 Apr, 2005
1 commit
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Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.Let it rip!
