05 Apr, 2020
1 commit
-
Pull drm hugepage support from Dave Airlie:
"This adds support for hugepages to TTM and has been tested with the
vmwgfx drivers, though I expect other drivers to start using it"* tag 'drm-next-2020-04-03-1' of git://anongit.freedesktop.org/drm/drm:
drm/vmwgfx: Hook up the helpers to align buffer objects
drm/vmwgfx: Introduce a huge page aligning TTM range manager
drm: Add a drm_get_unmapped_area() helper
drm/vmwgfx: Support huge page faults
drm/ttm, drm/vmwgfx: Support huge TTM pagefaults
mm: Add vmf_insert_pfn_xxx_prot() for huge page-table entries
mm: Split huge pages on write-notify or COW
mm: Introduce vma_is_special_huge
fs: Constify vma argument to vma_is_dax
04 Apr, 2020
1 commit
-
Pull cgroup updates from Tejun Heo:
- Christian extended clone3 so that processes can be spawned into
cgroups directly.This is not only neat in terms of semantics but also avoids grabbing
the global cgroup_threadgroup_rwsem for migration.- Daniel added !root xattr support to cgroupfs.
Userland already uses xattrs on cgroupfs for bookkeeping. This will
allow delegated cgroups to support such usages.- Prateek tried to make cpuset hotplug handling synchronous but that
led to possible deadlock scenarios. Reverted.- Other minor changes including release_agent_path handling cleanup.
* 'for-5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
docs: cgroup-v1: Document the cpuset_v2_mode mount option
Revert "cpuset: Make cpuset hotplug synchronous"
cgroupfs: Support user xattrs
kernfs: Add option to enable user xattrs
kernfs: Add removed_size out param for simple_xattr_set
kernfs: kvmalloc xattr value instead of kmalloc
cgroup: Restructure release_agent_path handling
selftests/cgroup: add tests for cloning into cgroups
clone3: allow spawning processes into cgroups
cgroup: add cgroup_may_write() helper
cgroup: refactor fork helpers
cgroup: add cgroup_get_from_file() helper
cgroup: unify attach permission checking
cpuset: Make cpuset hotplug synchronous
cgroup.c: Use built-in RCU list checking
kselftest/cgroup: add cgroup destruction test
cgroup: Clean up css_set task traversal
03 Apr, 2020
38 commits
-
Huge page-table entries for TTM
In order to reduce CPU usage [1] and in theory TLB misses this patchset enables
huge- and giant page-table entries for TTM and TTM-enabled graphics drivers.Signed-off-by: Dave Airlie
From: Thomas Hellstrom (VMware)
Link: https://patchwork.freedesktop.org/patch/msgid/20200325073102.6129-1-thomas_os@shipmail.org -
Pull percpu updates from Dennis Zhou:
"This is just a few documentation fixes for percpu refcount and bitmap
helpers that went in v5.6, and moving my emails to all be at korg"* 'for-5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/dennis/percpu:
percpu: update copyright emails to dennis@kernel.org
include/bitmap.h: add new functions to documentation
include/bitmap.h: add missing parameter in docs
percpu_ref: Fix comment regarding percpu_ref_init flags -
Merge updates from Andrew Morton:
"A large amount of MM, plenty more to come.Subsystems affected by this patch series:
- tools
- kthread
- kbuild
- scripts
- ocfs2
- vfs
- mm: slub, kmemleak, pagecache, gup, swap, memcg, pagemap, mremap,
sparsemem, kasan, pagealloc, vmscan, compaction, mempolicy,
hugetlbfs, hugetlb"* emailed patches from Andrew Morton : (155 commits)
include/linux/huge_mm.h: check PageTail in hpage_nr_pages even when !THP
mm/hugetlb: fix build failure with HUGETLB_PAGE but not HUGEBTLBFS
selftests/vm: fix map_hugetlb length used for testing read and write
mm/hugetlb: remove unnecessary memory fetch in PageHeadHuge()
mm/hugetlb.c: clean code by removing unnecessary initialization
hugetlb_cgroup: add hugetlb_cgroup reservation docs
hugetlb_cgroup: add hugetlb_cgroup reservation tests
hugetlb: support file_region coalescing again
hugetlb_cgroup: support noreserve mappings
hugetlb_cgroup: add accounting for shared mappings
hugetlb: disable region_add file_region coalescing
hugetlb_cgroup: add reservation accounting for private mappings
mm/hugetlb_cgroup: fix hugetlb_cgroup migration
hugetlb_cgroup: add interface for charge/uncharge hugetlb reservations
hugetlb_cgroup: add hugetlb_cgroup reservation counter
hugetlbfs: Use i_mmap_rwsem to address page fault/truncate race
hugetlbfs: use i_mmap_rwsem for more pmd sharing synchronization
mm/memblock.c: remove redundant assignment to variable max_addr
mm: mempolicy: require at least one nodeid for MPOL_PREFERRED
mm: mempolicy: use VM_BUG_ON_VMA in queue_pages_test_walk()
... -
Pull exec/proc updates from Eric Biederman:
"This contains two significant pieces of work: the work to sort out
proc_flush_task, and the work to solve a deadlock between strace and
exec.Fixing proc_flush_task so that it no longer requires a persistent
mount makes improvements to proc possible. The removal of the
persistent mount solves an old regression that that caused the hidepid
mount option to only work on remount not on mount. The regression was
found and reported by the Android folks. This further allows Alexey
Gladkov's work making proc mount options specific to an individual
mount of proc to move forward.The work on exec starts solving a long standing issue with exec that
it takes mutexes of blocking userspace applications, which makes exec
extremely deadlock prone. For the moment this adds a second mutex with
a narrower scope that handles all of the easy cases. Which makes the
tricky cases easy to spot. With a little luck the code to solve those
deadlocks will be ready by next merge window"* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (25 commits)
signal: Extend exec_id to 64bits
pidfd: Use new infrastructure to fix deadlocks in execve
perf: Use new infrastructure to fix deadlocks in execve
proc: io_accounting: Use new infrastructure to fix deadlocks in execve
proc: Use new infrastructure to fix deadlocks in execve
kernel/kcmp.c: Use new infrastructure to fix deadlocks in execve
kernel: doc: remove outdated comment cred.c
mm: docs: Fix a comment in process_vm_rw_core
selftests/ptrace: add test cases for dead-locks
exec: Fix a deadlock in strace
exec: Add exec_update_mutex to replace cred_guard_mutex
exec: Move exec_mmap right after de_thread in flush_old_exec
exec: Move cleanup of posix timers on exec out of de_thread
exec: Factor unshare_sighand out of de_thread and call it separately
exec: Only compute current once in flush_old_exec
pid: Improve the comment about waiting in zap_pid_ns_processes
proc: Remove the now unnecessary internal mount of proc
uml: Create a private mount of proc for mconsole
uml: Don't consult current to find the proc_mnt in mconsole_proc
proc: Use a list of inodes to flush from proc
... -
Commit f1e61557f023 ("mm: pack compound_dtor and compound_order into one
word in struct page") changed compound_dtor from a pointer to an array
index in order to pack it. To check if page has the hugeltbfs
compound_dtor, we can just compare the index directly without fetching the
function pointer. Said commit did that with PageHuge() and we can do the
same with PageHeadHuge() to make the code a bit smaller and faster.Signed-off-by: Vlastimil Babka
Signed-off-by: Andrew Morton
Reviewed-by: Mike Kravetz
Acked-by: David Rientjes
Acked-by: Kirill A. Shutemov
Cc: Neha Agarwal
Link: http://lkml.kernel.org/r/20200311172440.6988-1-vbabka@suse.cz
Signed-off-by: Linus Torvalds -
Previously variable 'check_addr' was initialized, but was not read later
before reassigning. So the initialization can be removed.Signed-off-by: Mateusz Nosek
Signed-off-by: Andrew Morton
Reviewed-by: Andrew Morton
Reviewed-by: Mike Kravetz
Link: http://lkml.kernel.org/r/20200303212354.25226-1-mateusznosek0@gmail.com
Signed-off-by: Linus Torvalds -
An earlier patch in this series disabled file_region coalescing in order
to hang the hugetlb_cgroup uncharge info on the file_region entries.This patch re-adds support for coalescing of file_region entries.
Essentially everytime we add an entry, we call a recursive function that
tries to coalesce the added region with the regions next to it. The worst
case call depth for this function is 3: one to coalesce with the region
next to it, one to coalesce to the region prev, and one to reach the base
case.This is an important performance optimization as private mappings add
their entries page by page, and we could incur big performance costs for
large mappings with lots of file_region entries in their resv_map.[almasrymina@google.com: fix CONFIG_CGROUP_HUGETLB ifdefs]
Link: http://lkml.kernel.org/r/20200214204544.231482-1-almasrymina@google.com
[almasrymina@google.com: remove check_coalesce_bug debug code]
Link: http://lkml.kernel.org/r/20200219233610.13808-1-almasrymina@google.com
Signed-off-by: Mina Almasry
Signed-off-by: Andrew Morton
Reviewed-by: Mike Kravetz
Acked-by: David Rientjes
Cc: Greg Thelen
Cc: Mike Kravetz
Cc: Sandipan Das
Cc: Shakeel Butt
Cc: Shuah Khan
Cc: Randy Dunlap
Link: http://lkml.kernel.org/r/20200211213128.73302-7-almasrymina@google.com
Signed-off-by: Linus Torvalds -
Support MAP_NORESERVE accounting as part of the new counter.
For each hugepage allocation, at allocation time we check if there is a
reservation for this allocation or not. If there is a reservation for
this allocation, then this allocation was charged at reservation time, and
we don't re-account it. If there is no reserevation for this allocation,
we charge the appropriate hugetlb_cgroup.The hugetlb_cgroup to uncharge for this allocation is stored in
page[3].private. We use new APIs added in an earlier patch to set this
pointer.Signed-off-by: Mina Almasry
Signed-off-by: Andrew Morton
Reviewed-by: Mike Kravetz
Cc: David Rientjes
Cc: Greg Thelen
Cc: Sandipan Das
Cc: Shakeel Butt
Cc: Shuah Khan
Link: http://lkml.kernel.org/r/20200211213128.73302-6-almasrymina@google.com
Signed-off-by: Linus Torvalds -
For shared mappings, the pointer to the hugetlb_cgroup to uncharge lives
in the resv_map entries, in file_region->reservation_counter.After a call to region_chg, we charge the approprate hugetlb_cgroup, and
if successful, we pass on the hugetlb_cgroup info to a follow up
region_add call. When a file_region entry is added to the resv_map via
region_add, we put the pointer to that cgroup in
file_region->reservation_counter. If charging doesn't succeed, we report
the error to the caller, so that the kernel fails the reservation.On region_del, which is when the hugetlb memory is unreserved, we also
uncharge the file_region->reservation_counter.[akpm@linux-foundation.org: forward declare struct file_region]
Signed-off-by: Mina Almasry
Signed-off-by: Andrew Morton
Reviewed-by: Mike Kravetz
Cc: David Rientjes
Cc: Greg Thelen
Cc: Mike Kravetz
Cc: Sandipan Das
Cc: Shakeel Butt
Cc: Shuah Khan
Link: http://lkml.kernel.org/r/20200211213128.73302-5-almasrymina@google.com
Signed-off-by: Linus Torvalds -
A follow up patch in this series adds hugetlb cgroup uncharge info the
file_region entries in resv->regions. The cgroup uncharge info may differ
for different regions, so they can no longer be coalesced at region_add
time. So, disable region coalescing in region_add in this patch.Behavior change:
Say a resv_map exists like this [0->1], [2->3], and [5->6].
Then a region_chg/add call comes in region_chg/add(f=0, t=5).
Old code would generate resv->regions: [0->5], [5->6].
New code would generate resv->regions: [0->1], [1->2], [2->3], [3->5],
[5->6].Special care needs to be taken to handle the resv->adds_in_progress
variable correctly. In the past, only 1 region would be added for every
region_chg and region_add call. But now, each call may add multiple
regions, so we can no longer increment adds_in_progress by 1 in
region_chg, or decrement adds_in_progress by 1 after region_add or
region_abort. Instead, region_chg calls add_reservation_in_range() to
count the number of regions needed and allocates those, and that info is
passed to region_add and region_abort to decrement adds_in_progress
correctly.We've also modified the assumption that region_add after region_chg never
fails. region_chg now pre-allocates at least 1 region for region_add. If
region_add needs more regions than region_chg has allocated for it, then
it may fail.[almasrymina@google.com: fix file_region entry allocations]
Link: http://lkml.kernel.org/r/20200219012736.20363-1-almasrymina@google.com
Signed-off-by: Mina Almasry
Signed-off-by: Andrew Morton
Reviewed-by: Mike Kravetz
Acked-by: David Rientjes
Cc: Sandipan Das
Cc: Shakeel Butt
Cc: Shuah Khan
Cc: Greg Thelen
Cc: Miguel Ojeda
Link: http://lkml.kernel.org/r/20200211213128.73302-4-almasrymina@google.com
Signed-off-by: Linus Torvalds -
Normally the pointer to the cgroup to uncharge hangs off the struct page,
and gets queried when it's time to free the page. With hugetlb_cgroup
reservations, this is not possible. Because it's possible for a page to
be reserved by one task and actually faulted in by another task.The best place to put the hugetlb_cgroup pointer to uncharge for
reservations is in the resv_map. But, because the resv_map has different
semantics for private and shared mappings, the code patch to
charge/uncharge shared and private mappings is different. This patch
implements charging and uncharging for private mappings.For private mappings, the counter to uncharge is in
resv_map->reservation_counter. On initializing the resv_map this is set
to NULL. On reservation of a region in private mapping, the tasks
hugetlb_cgroup is charged and the hugetlb_cgroup is placed is
resv_map->reservation_counter.On hugetlb_vm_op_close, we uncharge resv_map->reservation_counter.
[akpm@linux-foundation.org: forward declare struct resv_map]
Signed-off-by: Mina Almasry
Signed-off-by: Andrew Morton
Reviewed-by: Mike Kravetz
Acked-by: David Rientjes
Cc: Greg Thelen
Cc: Sandipan Das
Cc: Shakeel Butt
Cc: Shuah Khan
Link: http://lkml.kernel.org/r/20200211213128.73302-3-almasrymina@google.com
Signed-off-by: Linus Torvalds -
Commit c32300516047 ("hugetlb_cgroup: add interface for charge/uncharge
hugetlb reservations") mistakingly doesn't handle the migration of *both*
the reservation hugetlb_cgroup and the fault hugetlb_cgroup correctly.What should happen is that both cgroups shuold be queried from the old
page, then both set to NULL on the old page, then both inserted into the
new page.The mistake also creates the following warning:
mm/hugetlb_cgroup.c: In function 'hugetlb_cgroup_migrate':
mm/hugetlb_cgroup.c:777:25: warning: variable 'h_cg' set but not used
[-Wunused-but-set-variable]
struct hugetlb_cgroup *h_cg;
^~~~Solution is to add the missing steps, namly setting the reservation
hugetlb_cgroup to NULL on the old page, and setting the fault
hugetlb_cgroup on the new page.Fixes: c32300516047 ("hugetlb_cgroup: add interface for charge/uncharge hugetlb reservations")
Reported-by: Qian Cai
Signed-off-by: Mina Almasry
Signed-off-by: Andrew Morton
Cc: David Rientjes
Cc: Greg Thelen
Cc: Mike Kravetz
Cc: Sandipan Das
Cc: Shakeel Butt
Cc: Shuah Khan
Link: http://lkml.kernel.org/r/20200218194727.46995-1-almasrymina@google.com
Signed-off-by: Linus Torvalds -
Augments hugetlb_cgroup_charge_cgroup to be able to charge hugetlb usage
or hugetlb reservation counter.Adds a new interface to uncharge a hugetlb_cgroup counter via
hugetlb_cgroup_uncharge_counter.Integrates the counter with hugetlb_cgroup, via hugetlb_cgroup_init,
hugetlb_cgroup_have_usage, and hugetlb_cgroup_css_offline.Signed-off-by: Mina Almasry
Signed-off-by: Andrew Morton
Acked-by: Mike Kravetz
Acked-by: David Rientjes
Cc: Greg Thelen
Cc: Sandipan Das
Cc: Shakeel Butt
Cc: Shuah Khan
Link: http://lkml.kernel.org/r/20200211213128.73302-2-almasrymina@google.com
Signed-off-by: Linus Torvalds -
These counters will track hugetlb reservations rather than hugetlb memory
faulted in. This patch only adds the counter, following patches add the
charging and uncharging of the counter.This is patch 1 of an 9 patch series.
Problem:
Currently tasks attempting to reserve more hugetlb memory than is
available get a failure at mmap/shmget time. This is thanks to Hugetlbfs
Reservations [1]. However, if a task attempts to reserve more hugetlb
memory than its hugetlb_cgroup limit allows, the kernel will allow the
mmap/shmget call, but will SIGBUS the task when it attempts to fault in
the excess memory.We have users hitting their hugetlb_cgroup limits and thus we've been
looking at this failure mode. We'd like to improve this behavior such
that users violating the hugetlb_cgroup limits get an error on mmap/shmget
time, rather than getting SIGBUS'd when they try to fault the excess
memory in. This gives the user an opportunity to fallback more gracefully
to non-hugetlbfs memory for example.The underlying problem is that today's hugetlb_cgroup accounting happens
at hugetlb memory *fault* time, rather than at *reservation* time. Thus,
enforcing the hugetlb_cgroup limit only happens at fault time, and the
offending task gets SIGBUS'd.Proposed Solution:
A new page counter named
'hugetlb.xMB.rsvd.[limit|usage|max_usage]_in_bytes'. This counter has
slightly different semantics than
'hugetlb.xMB.[limit|usage|max_usage]_in_bytes':- While usage_in_bytes tracks all *faulted* hugetlb memory,
rsvd.usage_in_bytes tracks all *reserved* hugetlb memory and hugetlb
memory faulted in without a prior reservation.- If a task attempts to reserve more memory than limit_in_bytes allows,
the kernel will allow it to do so. But if a task attempts to reserve
more memory than rsvd.limit_in_bytes, the kernel will fail this
reservation.This proposal is implemented in this patch series, with tests to verify
functionality and show the usage.Alternatives considered:
1. A new cgroup, instead of only a new page_counter attached to the
existing hugetlb_cgroup. Adding a new cgroup seemed like a lot of code
duplication with hugetlb_cgroup. Keeping hugetlb related page counters
under hugetlb_cgroup seemed cleaner as well.2. Instead of adding a new counter, we considered adding a sysctl that
modifies the behavior of hugetlb.xMB.[limit|usage]_in_bytes, to do
accounting at reservation time rather than fault time. Adding a new
page_counter seems better as userspace could, if it wants, choose to
enforce different cgroups differently: one via limit_in_bytes, and
another via rsvd.limit_in_bytes. This could be very useful if you're
transitioning how hugetlb memory is partitioned on your system one
cgroup at a time, for example. Also, someone may find usage for both
limit_in_bytes and rsvd.limit_in_bytes concurrently, and this approach
gives them the option to do so.Testing:
- Added tests passing.
- Used libhugetlbfs for regression testing.[1]: https://www.kernel.org/doc/html/latest/vm/hugetlbfs_reserv.html
Signed-off-by: Mina Almasry
Signed-off-by: Andrew Morton
Reviewed-by: Mike Kravetz
Acked-by: David Rientjes
Cc: Shuah Khan
Cc: Shakeel Butt
Cc: Greg Thelen
Cc: Sandipan Das
Link: http://lkml.kernel.org/r/20200211213128.73302-1-almasrymina@google.com
Signed-off-by: Linus Torvalds -
hugetlbfs page faults can race with truncate and hole punch operations.
Current code in the page fault path attempts to handle this by 'backing
out' operations if we encounter the race. One obvious omission in the
current code is removing a page newly added to the page cache. This is
pretty straight forward to address, but there is a more subtle and
difficult issue of backing out hugetlb reservations. To handle this
correctly, the 'reservation state' before page allocation needs to be
noted so that it can be properly backed out. There are four distinct
possibilities for reservation state: shared/reserved, shared/no-resv,
private/reserved and private/no-resv. Backing out a reservation may
require memory allocation which could fail so that needs to be taken
into account as well.Instead of writing the required complicated code for this rare
occurrence, just eliminate the race. i_mmap_rwsem is now held in read
mode for the duration of page fault processing. Hold i_mmap_rwsem in
write mode when modifying i_size. In this way, truncation can not
proceed when page faults are being processed. In addition, i_size
will not change during fault processing so a single check can be made
to ensure faults are not beyond (proposed) end of file. Faults can
still race with hole punch, but that race is handled by existing code
and the use of hugetlb_fault_mutex.With this modification, checks for races with truncation in the page
fault path can be simplified and removed. remove_inode_hugepages no
longer needs to take hugetlb_fault_mutex in the case of truncation.
Comments are expanded to explain reasoning behind locking.Signed-off-by: Mike Kravetz
Signed-off-by: Andrew Morton
Cc: Andrea Arcangeli
Cc: "Aneesh Kumar K . V"
Cc: Davidlohr Bueso
Cc: Hugh Dickins
Cc: "Kirill A . Shutemov"
Cc: Michal Hocko
Cc: Naoya Horiguchi
Cc: Prakash Sangappa
Link: http://lkml.kernel.org/r/20200316205756.146666-3-mike.kravetz@oracle.com
Signed-off-by: Linus Torvalds -
Patch series "hugetlbfs: use i_mmap_rwsem for more synchronization", v2.
While discussing the issue with huge_pte_offset [1], I remembered that
there were more outstanding hugetlb races. These issues are:1) For shared pmds, huge PTE pointers returned by huge_pte_alloc can become
invalid via a call to huge_pmd_unshare by another thread.
2) hugetlbfs page faults can race with truncation causing invalid global
reserve counts and state.A previous attempt was made to use i_mmap_rwsem in this manner as
described at [2]. However, those patches were reverted starting with [3]
due to locking issues.To effectively use i_mmap_rwsem to address the above issues it needs to be
held (in read mode) during page fault processing. However, during fault
processing we need to lock the page we will be adding. Lock ordering
requires we take page lock before i_mmap_rwsem. Waiting until after
taking the page lock is too late in the fault process for the
synchronization we want to do.To address this lock ordering issue, the following patches change the lock
ordering for hugetlb pages. This is not too invasive as hugetlbfs
processing is done separate from core mm in many places. However, I don't
really like this idea. Much ugliness is contained in the new routine
hugetlb_page_mapping_lock_write() of patch 1.The only other way I can think of to address these issues is by catching
all the races. After catching a race, cleanup, backout, retry ... etc,
as needed. This can get really ugly, especially for huge page
reservations. At one time, I started writing some of the reservation
backout code for page faults and it got so ugly and complicated I went
down the path of adding synchronization to avoid the races. Any other
suggestions would be welcome.[1] https://lore.kernel.org/linux-mm/1582342427-230392-1-git-send-email-longpeng2@huawei.com/
[2] https://lore.kernel.org/linux-mm/20181222223013.22193-1-mike.kravetz@oracle.com/
[3] https://lore.kernel.org/linux-mm/20190103235452.29335-1-mike.kravetz@oracle.com
[4] https://lore.kernel.org/linux-mm/1584028670.7365.182.camel@lca.pw/
[5] https://lore.kernel.org/lkml/20200312183142.108df9ac@canb.auug.org.au/This patch (of 2):
While looking at BUGs associated with invalid huge page map counts, it was
discovered and observed that a huge pte pointer could become 'invalid' and
point to another task's page table. Consider the following:A task takes a page fault on a shared hugetlbfs file and calls
huge_pte_alloc to get a ptep. Suppose the returned ptep points to a
shared pmd.Now, another task truncates the hugetlbfs file. As part of truncation, it
unmaps everyone who has the file mapped. If the range being truncated is
covered by a shared pmd, huge_pmd_unshare will be called. For all but the
last user of the shared pmd, huge_pmd_unshare will clear the pud pointing
to the pmd. If the task in the middle of the page fault is not the last
user, the ptep returned by huge_pte_alloc now points to another task's
page table or worse. This leads to bad things such as incorrect page
map/reference counts or invalid memory references.To fix, expand the use of i_mmap_rwsem as follows:
- i_mmap_rwsem is held in read mode whenever huge_pmd_share is called.
huge_pmd_share is only called via huge_pte_alloc, so callers of
huge_pte_alloc take i_mmap_rwsem before calling. In addition, callers
of huge_pte_alloc continue to hold the semaphore until finished with
the ptep.
- i_mmap_rwsem is held in write mode whenever huge_pmd_unshare is called.One problem with this scheme is that it requires taking i_mmap_rwsem
before taking the page lock during page faults. This is not the order
specified in the rest of mm code. Handling of hugetlbfs pages is mostly
isolated today. Therefore, we use this alternative locking order for
PageHuge() pages.mapping->i_mmap_rwsem
hugetlb_fault_mutex (hugetlbfs specific page fault mutex)
page->flags PG_locked (lock_page)To help with lock ordering issues, hugetlb_page_mapping_lock_write() is
introduced to write lock the i_mmap_rwsem associated with a page.In most cases it is easy to get address_space via vma->vm_file->f_mapping.
However, in the case of migration or memory errors for anon pages we do
not have an associated vma. A new routine _get_hugetlb_page_mapping()
will use anon_vma to get address_space in these cases.Signed-off-by: Mike Kravetz
Signed-off-by: Andrew Morton
Cc: Michal Hocko
Cc: Hugh Dickins
Cc: Naoya Horiguchi
Cc: "Aneesh Kumar K . V"
Cc: Andrea Arcangeli
Cc: "Kirill A . Shutemov"
Cc: Davidlohr Bueso
Cc: Prakash Sangappa
Link: http://lkml.kernel.org/r/20200316205756.146666-2-mike.kravetz@oracle.com
Signed-off-by: Linus Torvalds -
The variable max_addr is being initialized with a value that is never read
and it is being updated later with a new value. The initialization is
redundant and can be removed.Signed-off-by: Colin Ian King
Signed-off-by: Andrew Morton
Reviewed-by: Pankaj Gupta
Reviewed-by: Mike Rapoport
Link: http://lkml.kernel.org/r/20200228235003.112718-1-colin.king@canonical.com
Addresses-Coverity: ("Unused value")
Signed-off-by: Linus Torvalds -
Using an empty (malformed) nodelist that is not caught during mount option
parsing leads to a stack-out-of-bounds access.The option string that was used was: "mpol=prefer:,". However,
MPOL_PREFERRED requires a single node number, which is not being provided
here.Add a check that 'nodes' is not empty after parsing for MPOL_PREFERRED's
nodeid.Fixes: 095f1fc4ebf3 ("mempolicy: rework shmem mpol parsing and display")
Reported-by: Entropy Moe
Reported-by: syzbot+b055b1a6b2b958707a21@syzkaller.appspotmail.com
Signed-off-by: Randy Dunlap
Signed-off-by: Andrew Morton
Tested-by: syzbot+b055b1a6b2b958707a21@syzkaller.appspotmail.com
Cc: Lee Schermerhorn
Link: http://lkml.kernel.org/r/89526377-7eb6-b662-e1d8-4430928abde9@infradead.org
Signed-off-by: Linus Torvalds -
The VM_BUG_ON() is already used by queue_pages_test_walk(), it sounds
better to dump more debug information by using VM_BUG_ON_VMA() to help
debugging.Signed-off-by: Yang Shi
Signed-off-by: Andrew Morton
Reviewed-by: Andrew Morton
Cc: "Li Xinhai"
Cc: Qian Cai
Link: http://lkml.kernel.org/r/1579068565-110432-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Linus Torvalds -
vma_migratable() is called to check if pages in vma can be migrated before
go ahead to further actions. Currently it is used in below code path:- task_numa_work
- mbind
- move_pagesFor hugetlb mapping, whether vma is migratable or not is determined by:
- CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
- arch_hugetlb_migration_supportedIssue: current code only checks for CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
alone, and no code should use it directly. (note that current code in
vma_migratable don't cause failure or bug because
unmap_and_move_huge_page() will catch unsupported hugepage and handle it
properly)This patch checks the two factors by hugepage_migration_supported for
impoving code logic and robustness. It will enable early bail out of
hugepage migration procedure, but because currently all architecture
supporting hugepage migration is able to support all page size, we would
not see performance gain with this patch applied.vma_migratable() is moved to mm/mempolicy.c, because of the circular
reference of mempolicy.h and hugetlb.h cause defining it as inline not
feasible.Signed-off-by: Li Xinhai
Signed-off-by: Andrew Morton
Reviewed-by: Mike Kravetz
Acked-by: Michal Hocko
Cc: Anshuman Khandual
Cc: Naoya Horiguchi
Link: http://lkml.kernel.org/r/1579786179-30633-1-git-send-email-lixinhai.lxh@gmail.com
Signed-off-by: Linus Torvalds -
MPOL_MF_STRICT is used in mbind() for purposes:
(1) MPOL_MF_STRICT is set alone without MPOL_MF_MOVE or
MPOL_MF_MOVE_ALL, to check if there is misplaced page and return -EIO;(2) MPOL_MF_STRICT is set with MPOL_MF_MOVE or MPOL_MF_MOVE_ALL, to
check if there is misplaced page which is failed to isolate, or page
is success on isolate but failed to move, and return -EIO.For non hugepage mapping, (1) and (2) are implemented as expectation. For
hugepage mapping, (1) is not implemented. And in (2), the part about
failed to isolate and report -EIO is not implemented.This patch implements the missed parts for hugepage mapping. Benefits
with it applied:- User space can apply same code logic to handle mbind() on hugepage and
non hugepage mapping;- Reliably using MPOL_MF_STRICT alone to check whether there is
misplaced page or not when bind policy on address range, especially for
address range which contains both hugepage and non hugepage mapping.Analysis of potential impact to existing users:
- If MPOL_MF_STRICT alone was previously used, hugetlb pages not
following the memory policy would not cause an EIO error. After this
change, hugetlb pages are treated like all other pages. If
MPOL_MF_STRICT alone is used and hugetlb pages do not follow memory
policy an EIO error will be returned.- For users who using MPOL_MF_STRICT with MPOL_MF_MOVE or
MPOL_MF_MOVE_ALL, the semantic about some pages could not be moved will
not be changed by this patch, because failed to isolate and failed to
move have same effects to users, so their existing code will not be
impacted.In mbind man page, the note about 'MPOL_MF_STRICT is ignored on huge page
mappings' can be removed after this patch is applied.Mike:
: The current behavior with MPOL_MF_STRICT and hugetlb pages is inconsistent
: and does not match documentation (as described above). The special
: behavior for hugetlb pages ideally should have been removed when hugetlb
: page migration was introduced. It is unlikely that anyone relies on
: today's inconsistent behavior, and removing one more case of special
: handling for hugetlb pages is a good thing.Signed-off-by: Li Xinhai
Signed-off-by: Andrew Morton
Reviewed-by: Mike Kravetz
Reviewed-by: Naoya Horiguchi
Cc: Michal Hocko
Cc: linux-man
Link: http://lkml.kernel.org/r/1581559627-6206-1-git-send-email-lixinhai.lxh@gmail.com
Signed-off-by: Linus Torvalds -
Previously 0 was assigned to variable 'last_migrated_pfn'. But the
variable is not read after that, so the assignment can be removed.Signed-off-by: Mateusz Nosek
Signed-off-by: Andrew Morton
Reviewed-by: Andrew Morton
Acked-by: Vlastimil Babka
Cc: Mel Gorman
Link: http://lkml.kernel.org/r/20200318174509.15021-1-mateusznosek0@gmail.com
Signed-off-by: Linus Torvalds -
Since commit 5bbe3547aa3ba ("mm: allow compaction of unevictable pages")
it is allowed to examine mlocked pages and compact them by default. On
-RT even minor pagefaults are problematic because it may take a few 100us
to resolve them and until then the task is blocked.Make compact_unevictable_allowed = 0 default and issue a warning on RT if
it is changed.[bigeasy@linutronix.de: v5]
Link: https://lore.kernel.org/linux-mm/20190710144138.qyn4tuttdq6h7kqx@linutronix.de/
Link: http://lkml.kernel.org/r/20200319165536.ovi75tsr2seared4@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior
Signed-off-by: Andrew Morton
Reviewed-by: Andrew Morton
Acked-by: Mel Gorman
Acked-by: Vlastimil Babka
Cc: Thomas Gleixner
Cc: Luis Chamberlain
Cc: Kees Cook
Cc: Iurii Zaikin
Cc: Vlastimil Babka
Link: https://lore.kernel.org/linux-mm/20190710144138.qyn4tuttdq6h7kqx@linutronix.de/
Link: http://lkml.kernel.org/r/20200303202225.nhqc3v5gwlb7x6et@linutronix.de
Signed-off-by: Linus Torvalds -
Dan reports:
The patch 5e1f0f098b46: "mm, compaction: capture a page under direct
compaction" from Mar 5, 2019, leads to the following Smatch complaint:mm/compaction.c:2321 compact_zone_order()
error: we previously assumed 'capture' could be null (see line 2313)mm/compaction.c
2288 static enum compact_result compact_zone_order(struct zone *zone, int order,
2289 gfp_t gfp_mask, enum compact_priority prio,
2290 unsigned int alloc_flags, int classzone_idx,
2291 struct page **capture)
^^^^^^^2313 if (capture)
^^^^^^^
Check for NULL2314 current->capture_control = &capc;
2315
2316 ret = compact_zone(&cc, &capc);
2317
2318 VM_BUG_ON(!list_empty(&cc.freepages));
2319 VM_BUG_ON(!list_empty(&cc.migratepages));
2320
2321 *capture = capc.page;
^^^^^^^^
Unchecked dereference.2322 current->capture_control = NULL;
2323In practice this is not an issue, as the only caller path passes non-NULL
capture:__alloc_pages_direct_compact()
struct page *page = NULL;
try_to_compact_pages(capture = &page);
compact_zone_order(capture = capture);So let's remove the unnecessary check, which should also make Smatch happy.
Fixes: 5e1f0f098b46 ("mm, compaction: capture a page under direct compaction")
Reported-by: Dan Carpenter
Suggested-by: Andrew Morton
Signed-off-by: Vlastimil Babka
Signed-off-by: Andrew Morton
Reviewed-by: Andrew Morton
Acked-by: Mel Gorman
Link: http://lkml.kernel.org/r/18b0df3c-0589-d96c-23fa-040798fee187@suse.cz
Signed-off-by: Linus Torvalds -
The code to implement THP migrations already exists, and the code for CMA
to clear out a region of memory already exists.Only a few small tweaks are needed to allow CMA to move THP memory when
attempting an allocation from alloc_contig_range.With these changes, migrating THPs from a CMA area works when allocating a
1GB hugepage from CMA memory.[riel@surriel.com: fix hugetlbfs pages per Mike, cleanup per Vlastimil]
Link: http://lkml.kernel.org/r/20200228104700.0af2f18d@imladris.surriel.com
Signed-off-by: Rik van Riel
Signed-off-by: Andrew Morton
Reviewed-by: Zi Yan
Reviewed-by: Vlastimil Babka
Cc: Michal Hocko
Cc: Vlastimil Babka
Cc: Mel Gorman
Cc: David Rientjes
Cc: Andrea Arcangeli
Cc: Mike Kravetz
Cc: Joonsoo Kim
Link: http://lkml.kernel.org/r/20200227213238.1298752-2-riel@surriel.com
Signed-off-by: Linus Torvalds -
Patch series "fix THP migration for CMA allocations", v2.
Transparent huge pages are allocated with __GFP_MOVABLE, and can end up in
CMA memory blocks. Transparent huge pages also have most of the
infrastructure in place to allow migration.However, a few pieces were missing, causing THP migration to fail when
attempting to use CMA to allocate 1GB hugepages.With these patches in place, THP migration from CMA blocks seems to work,
both for anonymous THPs and for tmpfs/shmem THPs.This patch (of 2):
Add information to struct compact_control to indicate that the allocator
would really like to clear out this specific part of memory, used by for
example CMA.Signed-off-by: Rik van Riel
Signed-off-by: Andrew Morton
Reviewed-by: Vlastimil Babka
Cc: Andrea Arcangeli
Cc: David Rientjes
Cc: Mel Gorman
Cc: Michal Hocko
Cc: Zi Yan
Cc: Joonsoo Kim
Link: http://lkml.kernel.org/r/20200227213238.1298752-1-riel@surriel.com
Signed-off-by: Linus Torvalds -
sc->memcg_low_skipped resets skipped_deactivate to 0 but this is not
needed as this code path is never reachable with skipped_deactivate != 0
due to previous sc->skipped_deactivate branch.[mhocko@kernel.org: rewrite changelog]
Signed-off-by: Mateusz Nosek
Signed-off-by: Andrew Morton
Acked-by: Johannes Weiner
Cc: Michal Hocko
Link: http://lkml.kernel.org/r/20200319165938.23354-1-mateusznosek0@gmail.com
Signed-off-by: Linus Torvalds -
This gives some size improvement:
$size mm/vmscan.o (before)
text data bss dec hex filename
53670 24123 12 77805 12fed mm/vmscan.o$size mm/vmscan.o (after)
text data bss dec hex filename
53648 24123 12 77783 12fd7 mm/vmscan.oSigned-off-by: Kirill Tkhai
Signed-off-by: Andrew Morton
Reviewed-by: Andrew Morton
Link: http://lkml.kernel.org/r/Message-ID:
Signed-off-by: Linus Torvalds -
Previously 0 was assigned to variable 'lruvec_size', but the variable was
never read later. So the assignment can be removed.Fixes: f87bccde6a7d ("mm/vmscan: remove unused lru_pages argument")
Signed-off-by: Mateusz Nosek
Signed-off-by: Andrew Morton
Reviewed-by: Matthew Wilcox (Oracle)
Reviewed-by: Wei Yang
Reviewed-by: David Hildenbrand
Link: http://lkml.kernel.org/r/20200229214022.11853-1-mateusznosek0@gmail.com
Signed-off-by: Linus Torvalds -
pgdat->kswapd_classzone_idx could be accessed concurrently in
wakeup_kswapd(). Plain writes and reads without any lock protection
result in data races. Fix them by adding a pair of READ|WRITE_ONCE() as
well as saving a branch (compilers might well optimize the original code
in an unintentional way anyway). While at it, also take care of
pgdat->kswapd_order and non-kswapd threads in allow_direct_reclaim(). The
data races were reported by KCSAN,BUG: KCSAN: data-race in wakeup_kswapd / wakeup_kswapd
write to 0xffff9f427ffff2dc of 4 bytes by task 7454 on cpu 13:
wakeup_kswapd+0xf1/0x400
wakeup_kswapd at mm/vmscan.c:3967
wake_all_kswapds+0x59/0xc0
wake_all_kswapds at mm/page_alloc.c:4241
__alloc_pages_slowpath+0xdcc/0x1290
__alloc_pages_slowpath at mm/page_alloc.c:4512
__alloc_pages_nodemask+0x3bb/0x450
alloc_pages_vma+0x8a/0x2c0
do_anonymous_page+0x16e/0x6f0
__handle_mm_fault+0xcd5/0xd40
handle_mm_fault+0xfc/0x2f0
do_page_fault+0x263/0x6f9
page_fault+0x34/0x401 lock held by mtest01/7454:
#0: ffff9f425afe8808 (&mm->mmap_sem#2){++++}, at:
do_page_fault+0x143/0x6f9
do_user_addr_fault at arch/x86/mm/fault.c:1405
(inlined by) do_page_fault at arch/x86/mm/fault.c:1539
irq event stamp: 6944085
count_memcg_event_mm+0x1a6/0x270
count_memcg_event_mm+0x119/0x270
__do_softirq+0x34c/0x57c
irq_exit+0xa2/0xc0read to 0xffff9f427ffff2dc of 4 bytes by task 7472 on cpu 38:
wakeup_kswapd+0xc8/0x400
wake_all_kswapds+0x59/0xc0
__alloc_pages_slowpath+0xdcc/0x1290
__alloc_pages_nodemask+0x3bb/0x450
alloc_pages_vma+0x8a/0x2c0
do_anonymous_page+0x16e/0x6f0
__handle_mm_fault+0xcd5/0xd40
handle_mm_fault+0xfc/0x2f0
do_page_fault+0x263/0x6f9
page_fault+0x34/0x401 lock held by mtest01/7472:
#0: ffff9f425a9ac148 (&mm->mmap_sem#2){++++}, at:
do_page_fault+0x143/0x6f9
irq event stamp: 6793561
count_memcg_event_mm+0x1a6/0x270
count_memcg_event_mm+0x119/0x270
__do_softirq+0x34c/0x57c
irq_exit+0xa2/0xc0BUG: KCSAN: data-race in kswapd / wakeup_kswapd
write to 0xffff90973ffff2dc of 4 bytes by task 820 on cpu 6:
kswapd+0x27c/0x8d0
kthread+0x1e0/0x200
ret_from_fork+0x27/0x50read to 0xffff90973ffff2dc of 4 bytes by task 6299 on cpu 0:
wakeup_kswapd+0xf3/0x450
wake_all_kswapds+0x59/0xc0
__alloc_pages_slowpath+0xdcc/0x1290
__alloc_pages_nodemask+0x3bb/0x450
alloc_pages_vma+0x8a/0x2c0
do_anonymous_page+0x170/0x700
__handle_mm_fault+0xc9f/0xd00
handle_mm_fault+0xfc/0x2f0
do_page_fault+0x263/0x6f9
page_fault+0x34/0x40Signed-off-by: Qian Cai
Signed-off-by: Andrew Morton
Reviewed-by: Andrew Morton
Cc: Marco Elver
Cc: Matthew Wilcox
Link: http://lkml.kernel.org/r/1582749472-5171-1-git-send-email-cai@lca.pw
Signed-off-by: Linus Torvalds -
kswapd kernel thread starts either with a CPU affinity set to the full cpu
mask of its target node or without any affinity at all if the node is
CPUless. There is a cpu hotplug callback (kswapd_cpu_online) that
implements an elaborate way to update this mask when a cpu is onlined.It is not really clear whether there is any actual benefit from this
scheme. Completely CPU-less NUMA nodes rarely gain a new CPU during
runtime. Drop the code for that reason. If there is a real usecase then
we can resurrect and simplify the code.[mhocko@suse.com rewrite changelog]
Suggested-by: Michal Hocko
Signed-off-by: Wei Yang
Signed-off-by: Andrew Morton
Acked-by: Michal Hocko
Cc: David Rientjes
Link: http://lkml.kernel.org/r/20200218224422.3407-1-richardw.yang@linux.intel.com
Signed-off-by: Linus Torvalds -
The commit 98fa15f34cb3 ("mm: replace all open encodings for
NUMA_NO_NODE") did the replacement across the kernel tree, but we got
some more in vmscan.c since then.Signed-off-by: Yang Shi
Signed-off-by: Andrew Morton
Reviewed-by: Anshuman Khandual
Acked-by: Minchan Kim
Acked-by: David Rientjes
Link: http://lkml.kernel.org/r/1581568298-45317-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Linus Torvalds -
Use mem_cgroup_is_root() API to check if memcg is root memcg instead of
open coding.Signed-off-by: Yang Shi
Signed-off-by: Andrew Morton
Reviewed-by: Andrew Morton
Reviewed-by: David Hildenbrand
Acked-by: Michal Hocko
Acked-by: David Rientjes
Link: http://lkml.kernel.org/r/1581398649-125989-2-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Linus Torvalds -
When kstrndup fails, no memory was allocated and we can exit directly.
[david@redhat.com: reword changelog]
Signed-off-by: Yang Shi
Signed-off-by: Andrew Morton
Reviewed-by: Andrew Morton
Reviewed-by: David Hildenbrand
Acked-by: David Rientjes
Link: http://lkml.kernel.org/r/1581398649-125989-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Linus Torvalds -
Simplify page_is_buddy() to reduce the redundant code for better code
readability.Signed-off-by: chenqiwu
Signed-off-by: Andrew Morton
Reviewed-by: Alexander Duyck
Reviewed-by: Matthew Wilcox (Oracle)
Reviewed-by: Vlastimil Babka
Acked-by: Pankaj Gupta
Link: http://lkml.kernel.org/r/1583853751-5525-1-git-send-email-qiwuchen55@gmail.com
Signed-off-by: Linus Torvalds -
Previously if branch condition was false, the assignment was not executed.
The assignment can be safely executed even when the condition is false
and it is not incorrect as it assigns the value of 'nodemask' to
'ac.nodemask' which already has the same value.So as the assignment can be executed unconditionally, the branch can be
removed.Signed-off-by: Mateusz Nosek
Signed-off-by: Andrew Morton
Reviewed-by: Matthew Wilcox (Oracle)
Link: http://lkml.kernel.org/r/20200307225335.31300-1-mateusznosek0@gmail.com
Signed-off-by: Linus Torvalds -
Use free_area_empty() API to replace list_empty() for better code
readability.Signed-off-by: chenqiwu
Signed-off-by: Andrew Morton
Reviewed-by: Matthew Wilcox (Oracle)
Link: http://lkml.kernel.org/r/1583674354-7713-1-git-send-email-qiwuchen55@gmail.com
Signed-off-by: Linus Torvalds -
This patch makes ALLOC_KSWAPD equal to __GFP_KSWAPD_RECLAIM (cast to int).
Thanks to that code like:
if (gfp_mask & __GFP_KSWAPD_RECLAIM)
alloc_flags |= ALLOC_KSWAPD;can be changed to:
alloc_flags |= (__force int) (gfp_mask &__GFP_KSWAPD_RECLAIM);
Thanks to this one branch less is generated in the assembly.
In case of ALLOC_KSWAPD flag two branches are saved, first one in code
that always executes in the beginning of page allocation and the second
one in loop in page allocator slowpath.Signed-off-by: Mateusz Nosek
Signed-off-by: Andrew Morton
Acked-by: Vlastimil Babka
Acked-by: Mel Gorman
Link: http://lkml.kernel.org/r/20200304162118.14784-1-mateusznosek0@gmail.com
Signed-off-by: Linus Torvalds
