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proc: move "struct proc_dir_entry" into kmem cache

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"struct proc_dir_entry" is variable sized because of 0-length trailing
array for name, however, because of SLAB padding allocations it is
possible to make "struct proc_dir_entry" fixed sized and allocate same
amount of memory.

It buys fine-grained debugging with poisoning and usercopy protection
which is not possible with kmalloc-* caches.

Currently, on 32-bit 91+ byte allocations go into kmalloc-128 and on
64-bit 147+ byte allocations go to kmalloc-192 anyway.

Additional memory is allocated only for 38/46+ byte long names which are
rare or may not even exist in the wild.

Link: http://lkml.kernel.org/r/20180223205504.GA17139@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alexey Dobriyan
2018-04-10 16:31:52 -07:00
committed by Linus Torvalds
parent c4219edf1d
commit b4884f2333
5 changed files with 52 additions and 23 deletions
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7
fs/proc/proc_net.c
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@@ -192,7 +192,7 @@ static __net_init int proc_net_ns_init(struct net *net)
int err;
err = -ENOMEM;
netd = kzalloc(sizeof(*netd) + 4, GFP_KERNEL);
netd = kmem_cache_zalloc(proc_dir_entry_cache, GFP_KERNEL);
if (!netd)
goto out;
@@ -201,6 +201,7 @@ static __net_init int proc_net_ns_init(struct net *net)
netd->nlink = 2;
netd->namelen = 3;
netd->parent = &proc_root;
netd->name = netd->inline_name;
memcpy(netd->name, "net", 4);
uid = make_kuid(net->user_ns, 0);
@@ -223,7 +224,7 @@ static __net_init int proc_net_ns_init(struct net *net)
return 0;
free_net:
kfree(netd);
pde_free(netd);
out:
return err;
}
@@ -231,7 +232,7 @@ out:
static __net_exit void proc_net_ns_exit(struct net *net)
{
remove_proc_entry("stat", net->proc_net);
kfree(net->proc_net);
pde_free(net->proc_net);
}
static struct pernet_operations __net_initdata proc_net_ns_ops = {