The patch titled
Subject: refcount: introduce __refcount_{add|inc}_not_zero_limited
has been added to the -mm mm-unstable branch. Its filename is
refcount-introduce-__refcount_addinc_not_zero_limited.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/refcount-introduce-__refcount_addinc_not_zero_limited.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Subject: refcount: introduce __refcount_{add|inc}_not_zero_limited
Date: Thu, 26 Dec 2024 09:07:03 -0800
Introduce functions to increase refcount but with a top limit above which
they will fail to increase. Setting the limit to 0 indicates no limit.
Link: https://lkml.kernel.org/r/20241226170710.1159679-12-surenb@xxxxxxxxxx
Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Hillf Danton <hdanton@xxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jann Horn <jannh@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: kernel test robot <oliver.sang@xxxxxxxxx>
Cc: Klara Modin <klarasmodin@xxxxxxxxx>
Cc: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Lokesh Gidra <lokeshgidra@xxxxxxxxxx>
Cc: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx>
Cc: Mateusz Guzik <mjguzik@xxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Pasha Tatashin <pasha.tatashin@xxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Shakeel Butt <shakeel.butt@xxxxxxxxx>
Cc: Sourav Panda <souravpanda@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/refcount.h | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)
--- a/include/linux/refcount.h~refcount-introduce-__refcount_addinc_not_zero_limited
+++ a/include/linux/refcount.h
@@ -137,13 +137,19 @@ static inline unsigned int refcount_read
}
static inline __must_check __signed_wrap
-bool __refcount_add_not_zero(int i, refcount_t *r, int *oldp)
+bool __refcount_add_not_zero_limited(int i, refcount_t *r, int *oldp,
+ int limit)
{
int old = refcount_read(r);
do {
if (!old)
break;
+ if (limit && old + i > limit) {
+ if (oldp)
+ *oldp = old;
+ return false;
+ }
} while (!atomic_try_cmpxchg_relaxed(&r->refs, &old, old + i));
if (oldp)
@@ -155,6 +161,12 @@ bool __refcount_add_not_zero(int i, refc
return old;
}
+static inline __must_check __signed_wrap
+bool __refcount_add_not_zero(int i, refcount_t *r, int *oldp)
+{
+ return __refcount_add_not_zero_limited(i, r, oldp, 0);
+}
+
/**
* refcount_add_not_zero - add a value to a refcount unless it is 0
* @i: the value to add to the refcount
@@ -213,6 +225,12 @@ static inline void refcount_add(int i, r
__refcount_add(i, r, NULL);
}
+static inline __must_check bool __refcount_inc_not_zero_limited(refcount_t *r,
+ int *oldp, int limit)
+{
+ return __refcount_add_not_zero_limited(1, r, oldp, limit);
+}
+
static inline __must_check bool __refcount_inc_not_zero(refcount_t *r, int *oldp)
{
return __refcount_add_not_zero(1, r, oldp);
_
Patches currently in -mm which might be from surenb@xxxxxxxxxx are
seqlock-add-raw_seqcount_try_begin.patch
mm-convert-mm_lock_seq-to-a-proper-seqcount.patch
mm-introduce-mmap_lock_speculate_try_beginretry.patch
mm-introduce-vma_start_read_locked_nested-helpers.patch
mm-move-per-vma-lock-into-vm_area_struct.patch
mm-mark-vma-as-detached-until-its-added-into-vma-tree.patch
mm-modify-vma_iter_store_gfp-to-indicate-if-its-storing-a-new-vma.patch
mm-mark-vmas-detached-upon-exit.patch
mm-nommu-fix-the-last-places-where-vma-is-not-locked-before-being-attached.patch
types-move-struct-rcuwait-into-typesh.patch
mm-allow-vma_start_read_locked-vma_start_read_locked_nested-to-fail.patch
mm-move-mmap_init_lock-out-of-the-header-file.patch
mm-uninline-the-main-body-of-vma_start_write.patch
refcount-introduce-__refcount_addinc_not_zero_limited.patch
mm-replace-vm_lock-and-detached-flag-with-a-reference-count.patch
mm-debug-print-vm_refcnt-state-when-dumping-the-vma.patch
mm-debug-print-vm_refcnt-state-when-dumping-the-vma-fix.patch
mm-remove-extra-vma_numab_state_init-call.patch
mm-prepare-lock_vma_under_rcu-for-vma-reuse-possibility.patch
mm-make-vma-cache-slab_typesafe_by_rcu.patch
docs-mm-document-latest-changes-to-vm_lock.patch
