Revision 03049269de433cb5fe2859be9ae4469ceb1163ed authored by Michal Hocko on 25 March 2016, 21:20:33 UTC, committed by Linus Torvalds on 25 March 2016, 23:37:42 UTC
wake_oom_reaper has allowed only 1 oom victim to be queued. The main reason for that was the simplicity as other solutions would require some way of queuing. The current approach is racy and that was deemed sufficient as the oom_reaper is considered a best effort approach to help with oom handling when the OOM victim cannot terminate in a reasonable time. The race could lead to missing an oom victim which can get stuck out_of_memory wake_oom_reaper cmpxchg // OK oom_reaper oom_reap_task __oom_reap_task oom_victim terminates atomic_inc_not_zero // fail out_of_memory wake_oom_reaper cmpxchg // fails task_to_reap = NULL This race requires 2 OOM invocations in a short time period which is not very likely but certainly not impossible. E.g. the original victim might have not released a lot of memory for some reason. The situation would improve considerably if wake_oom_reaper used a more robust queuing. This is what this patch implements. This means adding oom_reaper_list list_head into task_struct (eat a hole before embeded thread_struct for that purpose) and a oom_reaper_lock spinlock for queuing synchronization. wake_oom_reaper will then add the task on the queue and oom_reaper will dequeue it. Signed-off-by: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Andrea Argangeli <andrea@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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ablk_helper.c
/*
* Shared async block cipher helpers
*
* Copyright (c) 2012 Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
*
* Based on aesni-intel_glue.c by:
* Copyright (C) 2008, Intel Corp.
* Author: Huang Ying <ying.huang@intel.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
* USA
*
*/
#include <linux/kernel.h>
#include <linux/crypto.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/hardirq.h>
#include <crypto/algapi.h>
#include <crypto/cryptd.h>
#include <crypto/ablk_helper.h>
#include <asm/simd.h>
int ablk_set_key(struct crypto_ablkcipher *tfm, const u8 *key,
unsigned int key_len)
{
struct async_helper_ctx *ctx = crypto_ablkcipher_ctx(tfm);
struct crypto_ablkcipher *child = &ctx->cryptd_tfm->base;
int err;
crypto_ablkcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
crypto_ablkcipher_set_flags(child, crypto_ablkcipher_get_flags(tfm)
& CRYPTO_TFM_REQ_MASK);
err = crypto_ablkcipher_setkey(child, key, key_len);
crypto_ablkcipher_set_flags(tfm, crypto_ablkcipher_get_flags(child)
& CRYPTO_TFM_RES_MASK);
return err;
}
EXPORT_SYMBOL_GPL(ablk_set_key);
int __ablk_encrypt(struct ablkcipher_request *req)
{
struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req);
struct async_helper_ctx *ctx = crypto_ablkcipher_ctx(tfm);
struct blkcipher_desc desc;
desc.tfm = cryptd_ablkcipher_child(ctx->cryptd_tfm);
desc.info = req->info;
desc.flags = 0;
return crypto_blkcipher_crt(desc.tfm)->encrypt(
&desc, req->dst, req->src, req->nbytes);
}
EXPORT_SYMBOL_GPL(__ablk_encrypt);
int ablk_encrypt(struct ablkcipher_request *req)
{
struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req);
struct async_helper_ctx *ctx = crypto_ablkcipher_ctx(tfm);
if (!may_use_simd()) {
struct ablkcipher_request *cryptd_req =
ablkcipher_request_ctx(req);
*cryptd_req = *req;
ablkcipher_request_set_tfm(cryptd_req, &ctx->cryptd_tfm->base);
return crypto_ablkcipher_encrypt(cryptd_req);
} else {
return __ablk_encrypt(req);
}
}
EXPORT_SYMBOL_GPL(ablk_encrypt);
int ablk_decrypt(struct ablkcipher_request *req)
{
struct crypto_ablkcipher *tfm = crypto_ablkcipher_reqtfm(req);
struct async_helper_ctx *ctx = crypto_ablkcipher_ctx(tfm);
if (!may_use_simd()) {
struct ablkcipher_request *cryptd_req =
ablkcipher_request_ctx(req);
*cryptd_req = *req;
ablkcipher_request_set_tfm(cryptd_req, &ctx->cryptd_tfm->base);
return crypto_ablkcipher_decrypt(cryptd_req);
} else {
struct blkcipher_desc desc;
desc.tfm = cryptd_ablkcipher_child(ctx->cryptd_tfm);
desc.info = req->info;
desc.flags = 0;
return crypto_blkcipher_crt(desc.tfm)->decrypt(
&desc, req->dst, req->src, req->nbytes);
}
}
EXPORT_SYMBOL_GPL(ablk_decrypt);
void ablk_exit(struct crypto_tfm *tfm)
{
struct async_helper_ctx *ctx = crypto_tfm_ctx(tfm);
cryptd_free_ablkcipher(ctx->cryptd_tfm);
}
EXPORT_SYMBOL_GPL(ablk_exit);
int ablk_init_common(struct crypto_tfm *tfm, const char *drv_name)
{
struct async_helper_ctx *ctx = crypto_tfm_ctx(tfm);
struct cryptd_ablkcipher *cryptd_tfm;
cryptd_tfm = cryptd_alloc_ablkcipher(drv_name, CRYPTO_ALG_INTERNAL,
CRYPTO_ALG_INTERNAL);
if (IS_ERR(cryptd_tfm))
return PTR_ERR(cryptd_tfm);
ctx->cryptd_tfm = cryptd_tfm;
tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request) +
crypto_ablkcipher_reqsize(&cryptd_tfm->base);
return 0;
}
EXPORT_SYMBOL_GPL(ablk_init_common);
int ablk_init(struct crypto_tfm *tfm)
{
char drv_name[CRYPTO_MAX_ALG_NAME];
snprintf(drv_name, sizeof(drv_name), "__driver-%s",
crypto_tfm_alg_driver_name(tfm));
return ablk_init_common(tfm, drv_name);
}
EXPORT_SYMBOL_GPL(ablk_init);
MODULE_LICENSE("GPL");
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