Merge branch 'akpm' (patches from Andrew)

Merge misc updates from Andrew Morton:
 "257 patches.

  Subsystems affected by this patch series: scripts, ocfs2, vfs, and
  mm (slab-generic, slab, slub, kconfig, dax, kasan, debug, pagecache,
  gup, swap, memcg, pagemap, mprotect, mremap, iomap, tracing, vmalloc,
  pagealloc, memory-failure, hugetlb, userfaultfd, vmscan, tools,
  memblock, oom-kill, hugetlbfs, migration, thp, readahead, nommu, ksm,
  vmstat, madvise, memory-hotplug, rmap, zsmalloc, highmem, zram,
  cleanups, kfence, and damon)"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (257 commits)
  mm/damon: remove return value from before_terminate callback
  mm/damon: fix a few spelling mistakes in comments and a pr_debug message
  mm/damon: simplify stop mechanism
  Docs/admin-guide/mm/pagemap: wordsmith page flags descriptions
  Docs/admin-guide/mm/damon/start: simplify the content
  Docs/admin-guide/mm/damon/start: fix a wrong link
  Docs/admin-guide/mm/damon/start: fix wrong example commands
  mm/damon/dbgfs: add adaptive_targets list check before enable monitor_on
  mm/damon: remove unnecessary variable initialization
  Documentation/admin-guide/mm/damon: add a document for DAMON_RECLAIM
  mm/damon: introduce DAMON-based Reclamation (DAMON_RECLAIM)
  selftests/damon: support watermarks
  mm/damon/dbgfs: support watermarks
  mm/damon/schemes: activate schemes based on a watermarks mechanism
  tools/selftests/damon: update for regions prioritization of schemes
  mm/damon/dbgfs: support prioritization weights
  mm/damon/vaddr,paddr: support pageout prioritization
  mm/damon/schemes: prioritize regions within the quotas
  mm/damon/selftests: support schemes quotas
  mm/damon/dbgfs: support quotas of schemes
  ...

1 files changed, 19 insertions, 4 deletions

diff --git a/Documentation/dev-tools/kfence.rst b/Documentation/dev-tools/kfence.rst
index 0fbe3308bf37..ac6b89d1a8c3 100644
--- a/Documentation/dev-tools/kfence.rst
+++ b/Documentation/dev-tools/kfence.rst
@@ -231,10 +231,14 @@ Guarded allocations are set up based on the sample interval. After expiration
 of the sample interval, the next allocation through the main allocator (SLAB or
 SLUB) returns a guarded allocation from the KFENCE object pool (allocation
 sizes up to PAGE_SIZE are supported). At this point, the timer is reset, and
-the next allocation is set up after the expiration of the interval. To "gate" a
-KFENCE allocation through the main allocator's fast-path without overhead,
-KFENCE relies on static branches via the static keys infrastructure. The static
-branch is toggled to redirect the allocation to KFENCE.
+the next allocation is set up after the expiration of the interval.
+
+When using ``CONFIG_KFENCE_STATIC_KEYS=y``, KFENCE allocations are "gated"
+through the main allocator's fast-path by relying on static branches via the
+static keys infrastructure. The static branch is toggled to redirect the
+allocation to KFENCE. Depending on sample interval, target workloads, and
+system architecture, this may perform better than the simple dynamic branch.
+Careful benchmarking is recommended.
 
 KFENCE objects each reside on a dedicated page, at either the left or right
 page boundaries selected at random. The pages to the left and right of the
@@ -269,6 +273,17 @@ tail of KFENCE's freelist, so that the least recently freed objects are reused
 first, and the chances of detecting use-after-frees of recently freed objects
 is increased.
 
+If pool utilization reaches 75% (default) or above, to reduce the risk of the
+pool eventually being fully occupied by allocated objects yet ensure diverse
+coverage of allocations, KFENCE limits currently covered allocations of the
+same source from further filling up the pool. The "source" of an allocation is
+based on its partial allocation stack trace. A side-effect is that this also
+limits frequent long-lived allocations (e.g. pagecache) of the same source
+filling up the pool permanently, which is the most common risk for the pool
+becoming full and the sampled allocation rate dropping to zero. The threshold
+at which to start limiting currently covered allocations can be configured via
+the boot parameter ``kfence.skip_covered_thresh`` (pool usage%).
+
 Interface
 ---------