The patch titled
Subject: ipc sem: use kvmalloc for sem_undo allocation
has been added to the -mm tree. Its filename is
ipc-sem-use-kvmalloc-for-sem_undo-allocation.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/ipc-sem-use-kvmalloc-for-sem_undo-allocation.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/ipc-sem-use-kvmalloc-for-sem_undo-allocation.patch
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------------------------------------------------------
From: Vasily Averin <vvs@xxxxxxxxxxxxx>
Subject: ipc sem: use kvmalloc for sem_undo allocation
Patch series "ipc: allocations cleanup", v2.
Some ipc objects use the wrong allocation functions: small objects can use
kmalloc(), and vice versa, potentially large objects can use kmalloc().
This patch (of 2):
Size of sem_undo can exceed one page and with the maximum possible nsems =
32000 it can grow up to 64Kb. Let's switch its allocation to kvmalloc to
avoid user-triggered disruptive actions like OOM killer in case of
high-order memory shortage.
User triggerable high order allocations are quite a problem on heavily
fragmented systems. They can be a DoS vector.
Link: https://lkml.kernel.org/r/ebc3ac79-3190-520d-81ce-22ad194986ec@xxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/a6354fd9-2d55-2e63-dd4d-fa7dc1d11134@xxxxxxxxxxxxx
Signed-off-by: Vasily Averin <vvs@xxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Acked-by: Roman Gushchin <guro@xxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Dmitry Safonov <0x7f454c46@xxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
ipc/sem.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
--- a/ipc/sem.c~ipc-sem-use-kvmalloc-for-sem_undo-allocation
+++ a/ipc/sem.c
@@ -1152,7 +1152,7 @@ static void freeary(struct ipc_namespace
un->semid = -1;
list_del_rcu(&un->list_proc);
spin_unlock(&un->ulp->lock);
- kfree_rcu(un, rcu);
+ kvfree_rcu(un, rcu);
}
/* Wake up all pending processes and let them fail with EIDRM. */
@@ -1935,7 +1935,8 @@ static struct sem_undo *find_alloc_undo(
rcu_read_unlock();
/* step 2: allocate new undo structure */
- new = kzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems, GFP_KERNEL);
+ new = kvzalloc(sizeof(struct sem_undo) + sizeof(short)*nsems,
+ GFP_KERNEL);
if (!new) {
ipc_rcu_putref(&sma->sem_perm, sem_rcu_free);
return ERR_PTR(-ENOMEM);
@@ -1947,7 +1948,7 @@ static struct sem_undo *find_alloc_undo(
if (!ipc_valid_object(&sma->sem_perm)) {
sem_unlock(sma, -1);
rcu_read_unlock();
- kfree(new);
+ kvfree(new);
un = ERR_PTR(-EIDRM);
goto out;
}
@@ -1958,7 +1959,7 @@ static struct sem_undo *find_alloc_undo(
*/
un = lookup_undo(ulp, semid);
if (un) {
- kfree(new);
+ kvfree(new);
goto success;
}
/* step 5: initialize & link new undo structure */
@@ -2418,7 +2419,7 @@ void exit_sem(struct task_struct *tsk)
rcu_read_unlock();
wake_up_q(&wake_q);
- kfree_rcu(un, rcu);
+ kvfree_rcu(un, rcu);
}
kfree(ulp);
}
_
Patches currently in -mm which might be from vvs@xxxxxxxxxxxxx are
ipc-sem-use-kvmalloc-for-sem_undo-allocation.patch
ipc-use-kmalloc-for-msg_queue-and-shmid_kernel.patch
