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authorLinus Torvalds <torvalds@linux-foundation.org>2019-10-08 02:04:19 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2019-10-08 02:04:19 +0300
commiteda57a0e42998d1d403187844faa86c9a3ab2fd0 (patch)
treefd49b5f7b3c6dfb5cdd49ec8bed967d387452c3c /Documentation
parentc512c69187197fe08026cb5bbe7b9709f4f89b73 (diff)
parent59bb47985c1db229ccff8c5deebecd54fc77d2a9 (diff)
downloadlinux-eda57a0e42998d1d403187844faa86c9a3ab2fd0.tar.xz
Merge branch 'akpm' (patches from Andrew)
Merge misc fixes from Andrew Morton: "The usual shower of hotfixes. Chris's memcg patches aren't actually fixes - they're mature but a few niggling review issues were late to arrive. The ocfs2 fixes are quite old - those took some time to get reviewer attention. Subsystems affected by this patch series: ocfs2, hotfixes, mm/memcg, mm/slab-generic" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: mm, sl[aou]b: guarantee natural alignment for kmalloc(power-of-two) mm, sl[ou]b: improve memory accounting mm, memcg: make scan aggression always exclude protection mm, memcg: make memory.emin the baseline for utilisation determination mm, memcg: proportional memory.{low,min} reclaim mm/vmpressure.c: fix a signedness bug in vmpressure_register_event() mm/page_alloc.c: fix a crash in free_pages_prepare() mm/z3fold.c: claim page in the beginning of free kernel/sysctl.c: do not override max_threads provided by userspace memcg: only record foreign writebacks with dirty pages when memcg is not disabled mm: fix -Wmissing-prototypes warnings writeback: fix use-after-free in finish_writeback_work() mm/memremap: drop unused SECTION_SIZE and SECTION_MASK panic: ensure preemption is disabled during panic() fs: ocfs2: fix a possible null-pointer dereference in ocfs2_info_scan_inode_alloc() fs: ocfs2: fix a possible null-pointer dereference in ocfs2_write_end_nolock() fs: ocfs2: fix possible null-pointer dereferences in ocfs2_xa_prepare_entry() ocfs2: clear zero in unaligned direct IO
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/admin-guide/cgroup-v2.rst20
-rw-r--r--Documentation/core-api/memory-allocation.rst4
2 files changed, 18 insertions, 6 deletions
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index 0fa8c0e615c2..5361ebec3361 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -615,8 +615,8 @@ on an IO device and is an example of this type.
Protections
-----------
-A cgroup is protected to be allocated upto the configured amount of
-the resource if the usages of all its ancestors are under their
+A cgroup is protected upto the configured amount of the resource
+as long as the usages of all its ancestors are under their
protected levels. Protections can be hard guarantees or best effort
soft boundaries. Protections can also be over-committed in which case
only upto the amount available to the parent is protected among
@@ -1096,7 +1096,10 @@ PAGE_SIZE multiple when read back.
is within its effective min boundary, the cgroup's memory
won't be reclaimed under any conditions. If there is no
unprotected reclaimable memory available, OOM killer
- is invoked.
+ is invoked. Above the effective min boundary (or
+ effective low boundary if it is higher), pages are reclaimed
+ proportionally to the overage, reducing reclaim pressure for
+ smaller overages.
Effective min boundary is limited by memory.min values of
all ancestor cgroups. If there is memory.min overcommitment
@@ -1118,7 +1121,10 @@ PAGE_SIZE multiple when read back.
Best-effort memory protection. If the memory usage of a
cgroup is within its effective low boundary, the cgroup's
memory won't be reclaimed unless memory can be reclaimed
- from unprotected cgroups.
+ from unprotected cgroups. Above the effective low boundary (or
+ effective min boundary if it is higher), pages are reclaimed
+ proportionally to the overage, reducing reclaim pressure for
+ smaller overages.
Effective low boundary is limited by memory.low values of
all ancestor cgroups. If there is memory.low overcommitment
@@ -2482,8 +2488,10 @@ system performance due to overreclaim, to the point where the feature
becomes self-defeating.
The memory.low boundary on the other hand is a top-down allocated
-reserve. A cgroup enjoys reclaim protection when it's within its low,
-which makes delegation of subtrees possible.
+reserve. A cgroup enjoys reclaim protection when it's within its
+effective low, which makes delegation of subtrees possible. It also
+enjoys having reclaim pressure proportional to its overage when
+above its effective low.
The original high boundary, the hard limit, is defined as a strict
limit that can not budge, even if the OOM killer has to be called.
diff --git a/Documentation/core-api/memory-allocation.rst b/Documentation/core-api/memory-allocation.rst
index 7744aa3bf2e0..939e3dfc86e9 100644
--- a/Documentation/core-api/memory-allocation.rst
+++ b/Documentation/core-api/memory-allocation.rst
@@ -98,6 +98,10 @@ limited. The actual limit depends on the hardware and the kernel
configuration, but it is a good practice to use `kmalloc` for objects
smaller than page size.
+The address of a chunk allocated with `kmalloc` is aligned to at least
+ARCH_KMALLOC_MINALIGN bytes. For sizes which are a power of two, the
+alignment is also guaranteed to be at least the respective size.
+
For large allocations you can use :c:func:`vmalloc` and
:c:func:`vzalloc`, or directly request pages from the page
allocator. The memory allocated by `vmalloc` and related functions is