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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deflate.c
/*
* Cryptographic API.
*
* Deflate algorithm (RFC 1951), implemented here primarily for use
* by IPCOMP (RFC 3173 & RFC 2394).
*
* Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
*
* 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.
*
* FIXME: deflate transforms will require up to a total of about 436k of kernel
* memory on i386 (390k for compression, the rest for decompression), as the
* current zlib kernel code uses a worst case pre-allocation system by default.
* This needs to be fixed so that the amount of memory required is properly
* related to the winbits and memlevel parameters.
*
* The default winbits of 11 should suit most packets, and it may be something
* to configure on a per-tfm basis in the future.
*
* Currently, compression history is not maintained between tfm calls, as
* it is not needed for IPCOMP and keeps the code simpler. It can be
* implemented if someone wants it.
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/crypto.h>
#include <linux/zlib.h>
#include <linux/vmalloc.h>
#include <linux/interrupt.h>
#include <linux/mm.h>
#include <linux/net.h>
#define DEFLATE_DEF_LEVEL Z_DEFAULT_COMPRESSION
#define DEFLATE_DEF_WINBITS 11
#define DEFLATE_DEF_MEMLEVEL MAX_MEM_LEVEL
struct deflate_ctx {
struct z_stream_s comp_stream;
struct z_stream_s decomp_stream;
};
static int deflate_comp_init(struct deflate_ctx *ctx)
{
int ret = 0;
struct z_stream_s *stream = &ctx->comp_stream;
stream->workspace = vzalloc(zlib_deflate_workspacesize(
-DEFLATE_DEF_WINBITS, DEFLATE_DEF_MEMLEVEL));
if (!stream->workspace) {
ret = -ENOMEM;
goto out;
}
ret = zlib_deflateInit2(stream, DEFLATE_DEF_LEVEL, Z_DEFLATED,
-DEFLATE_DEF_WINBITS, DEFLATE_DEF_MEMLEVEL,
Z_DEFAULT_STRATEGY);
if (ret != Z_OK) {
ret = -EINVAL;
goto out_free;
}
out:
return ret;
out_free:
vfree(stream->workspace);
goto out;
}
static int deflate_decomp_init(struct deflate_ctx *ctx)
{
int ret = 0;
struct z_stream_s *stream = &ctx->decomp_stream;
stream->workspace = vzalloc(zlib_inflate_workspacesize());
if (!stream->workspace) {
ret = -ENOMEM;
goto out;
}
ret = zlib_inflateInit2(stream, -DEFLATE_DEF_WINBITS);
if (ret != Z_OK) {
ret = -EINVAL;
goto out_free;
}
out:
return ret;
out_free:
vfree(stream->workspace);
goto out;
}
static void deflate_comp_exit(struct deflate_ctx *ctx)
{
zlib_deflateEnd(&ctx->comp_stream);
vfree(ctx->comp_stream.workspace);
}
static void deflate_decomp_exit(struct deflate_ctx *ctx)
{
zlib_inflateEnd(&ctx->decomp_stream);
vfree(ctx->decomp_stream.workspace);
}
static int deflate_init(struct crypto_tfm *tfm)
{
struct deflate_ctx *ctx = crypto_tfm_ctx(tfm);
int ret;
ret = deflate_comp_init(ctx);
if (ret)
goto out;
ret = deflate_decomp_init(ctx);
if (ret)
deflate_comp_exit(ctx);
out:
return ret;
}
static void deflate_exit(struct crypto_tfm *tfm)
{
struct deflate_ctx *ctx = crypto_tfm_ctx(tfm);
deflate_comp_exit(ctx);
deflate_decomp_exit(ctx);
}
static int deflate_compress(struct crypto_tfm *tfm, const u8 *src,
unsigned int slen, u8 *dst, unsigned int *dlen)
{
int ret = 0;
struct deflate_ctx *dctx = crypto_tfm_ctx(tfm);
struct z_stream_s *stream = &dctx->comp_stream;
ret = zlib_deflateReset(stream);
if (ret != Z_OK) {
ret = -EINVAL;
goto out;
}
stream->next_in = (u8 *)src;
stream->avail_in = slen;
stream->next_out = (u8 *)dst;
stream->avail_out = *dlen;
ret = zlib_deflate(stream, Z_FINISH);
if (ret != Z_STREAM_END) {
ret = -EINVAL;
goto out;
}
ret = 0;
*dlen = stream->total_out;
out:
return ret;
}
static int deflate_decompress(struct crypto_tfm *tfm, const u8 *src,
unsigned int slen, u8 *dst, unsigned int *dlen)
{
int ret = 0;
struct deflate_ctx *dctx = crypto_tfm_ctx(tfm);
struct z_stream_s *stream = &dctx->decomp_stream;
ret = zlib_inflateReset(stream);
if (ret != Z_OK) {
ret = -EINVAL;
goto out;
}
stream->next_in = (u8 *)src;
stream->avail_in = slen;
stream->next_out = (u8 *)dst;
stream->avail_out = *dlen;
ret = zlib_inflate(stream, Z_SYNC_FLUSH);
/*
* Work around a bug in zlib, which sometimes wants to taste an extra
* byte when being used in the (undocumented) raw deflate mode.
* (From USAGI).
*/
if (ret == Z_OK && !stream->avail_in && stream->avail_out) {
u8 zerostuff = 0;
stream->next_in = &zerostuff;
stream->avail_in = 1;
ret = zlib_inflate(stream, Z_FINISH);
}
if (ret != Z_STREAM_END) {
ret = -EINVAL;
goto out;
}
ret = 0;
*dlen = stream->total_out;
out:
return ret;
}
static struct crypto_alg alg = {
.cra_name = "deflate",
.cra_flags = CRYPTO_ALG_TYPE_COMPRESS,
.cra_ctxsize = sizeof(struct deflate_ctx),
.cra_module = THIS_MODULE,
.cra_init = deflate_init,
.cra_exit = deflate_exit,
.cra_u = { .compress = {
.coa_compress = deflate_compress,
.coa_decompress = deflate_decompress } }
};
static int __init deflate_mod_init(void)
{
return crypto_register_alg(&alg);
}
static void __exit deflate_mod_fini(void)
{
crypto_unregister_alg(&alg);
}
module_init(deflate_mod_init);
module_exit(deflate_mod_fini);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Deflate Compression Algorithm for IPCOMP");
MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
MODULE_ALIAS_CRYPTO("deflate");
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