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mm/mempolicy: protect task interleave functions with tsk->mems_allowed_seq 

In the event of rebind, pol->nodemask can change at the same time as an
allocation occurs.  We can detect this with tsk->mems_allowed_seq and
prevent a miscount or an allocation failure from occurring.

The same thing happens in the allocators to detect failure, but this can
prevent spurious failures in a much smaller critical section.

[gourry.memverge@gmail.com: weighted interleave checks wrong parameter]
  Link: https://lkml.kernel.org/r/20240206192853.3589-1-gregory.price@memverge.com
Link: https://lkml.kernel.org/r/20240202170238.90004-5-gregory.price@memverge.com
Signed-off-by: Gregory Price <gregory.price@memverge.com>
Suggested-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Hasan Al Maruf <Hasan.Maruf@amd.com>
Cc: Honggyu Kim <honggyu.kim@sk.com>
Cc: Hyeongtak Ji <hyeongtak.ji@sk.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Ravi Jonnalagadda <ravis.opensrc@micron.com>
Cc: Srinivasulu Thanneeru <sthanneeru.opensrc@micron.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Gregory Price 2024-02-02 12:02:38 -05:00 committed by Andrew Morton
parent fa3bea4e1f
commit 274519ed41
1 changed files with 23 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
mm/mempolicy.c
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@ -1874,11 +1874,17 @@ bool apply_policy_zone(struct mempolicy *policy, enum zone_type zone)
static unsigned int weighted_interleave_nodes(struct mempolicy *policy)
{
unsigned int node = current->il_prev;
unsigned int node;
unsigned int cpuset_mems_cookie;
retry:
/* to prevent miscount use tsk->mems_allowed_seq to detect rebind */
cpuset_mems_cookie = read_mems_allowed_begin();
node = current->il_prev;
if (!current->il_weight || !node_isset(node, policy->nodes)) {
node = next_node_in(node, policy->nodes);
/* can only happen if nodemask is being rebound */
if (read_mems_allowed_retry(cpuset_mems_cookie))
goto retry;
if (node == MAX_NUMNODES)
return node;
current->il_prev = node;
@ -1892,8 +1898,14 @@ static unsigned int weighted_interleave_nodes(struct mempolicy *policy)
static unsigned int interleave_nodes(struct mempolicy *policy)
{
unsigned int nid;
unsigned int cpuset_mems_cookie;
/* to prevent miscount, use tsk->mems_allowed_seq to detect rebind */
do {
cpuset_mems_cookie = read_mems_allowed_begin();
nid = next_node_in(current->il_prev, policy->nodes);
} while (read_mems_allowed_retry(cpuset_mems_cookie));
nid = next_node_in(current->il_prev, policy->nodes);
if (nid < MAX_NUMNODES)
current->il_prev = nid;
return nid;
@ -2370,6 +2382,7 @@ static unsigned long alloc_pages_bulk_array_weighted_interleave(gfp_t gfp,
struct page **page_array)
{
struct task_struct *me = current;
unsigned int cpuset_mems_cookie;
unsigned long total_allocated = 0;
unsigned long nr_allocated = 0;
unsigned long rounds;
@ -2387,7 +2400,13 @@ static unsigned long alloc_pages_bulk_array_weighted_interleave(gfp_t gfp,
if (!nr_pages)
return 0;
nnodes = read_once_policy_nodemask(pol, &nodes);
/* read the nodes onto the stack, retry if done during rebind */
do {
cpuset_mems_cookie = read_mems_allowed_begin();
nnodes = read_once_policy_nodemask(pol, &nodes);
} while (read_mems_allowed_retry(cpuset_mems_cookie));
/* if the nodemask has become invalid, we cannot do anything */
if (!nnodes)
return 0;