Revision 6bc9b56433b76e40d11099338d27fbc5cd2935ca authored by Naoya Horiguchi on 24 August 2018, 00:00:38 UTC, committed by Linus Torvalds on 24 August 2018, 01:48:43 UTC
Patch series "mm: soft-offline: fix race against page allocation". Xishi recently reported the issue about race on reusing the target pages of soft offlining. Discussion and analysis showed that we need make sure that setting PG_hwpoison should be done in the right place under zone->lock for soft offline. 1/2 handles free hugepage's case, and 2/2 hanldes free buddy page's case. This patch (of 2): There's a race condition between soft offline and hugetlb_fault which causes unexpected process killing and/or hugetlb allocation failure. The process killing is caused by the following flow: CPU 0 CPU 1 CPU 2 soft offline get_any_page // find the hugetlb is free mmap a hugetlb file page fault ... hugetlb_fault hugetlb_no_page alloc_huge_page // succeed soft_offline_free_page // set hwpoison flag mmap the hugetlb file page fault ... hugetlb_fault hugetlb_no_page find_lock_page return VM_FAULT_HWPOISON mm_fault_error do_sigbus // kill the process The hugetlb allocation failure comes from the following flow: CPU 0 CPU 1 mmap a hugetlb file // reserve all free page but don't fault-in soft offline get_any_page // find the hugetlb is free soft_offline_free_page // set hwpoison flag dissolve_free_huge_page // fail because all free hugepages are reserved page fault ... hugetlb_fault hugetlb_no_page alloc_huge_page ... dequeue_huge_page_node_exact // ignore hwpoisoned hugepage // and finally fail due to no-mem The root cause of this is that current soft-offline code is written based on an assumption that PageHWPoison flag should be set at first to avoid accessing the corrupted data. This makes sense for memory_failure() or hard offline, but does not for soft offline because soft offline is about corrected (not uncorrected) error and is safe from data lost. This patch changes soft offline semantics where it sets PageHWPoison flag only after containment of the error page completes successfully. Link: http://lkml.kernel.org/r/1531452366-11661-2-git-send-email-n-horiguchi@ah.jp.nec.com Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Reported-by: Xishi Qiu <xishi.qiuxishi@alibaba-inc.com> Suggested-by: Xishi Qiu <xishi.qiuxishi@alibaba-inc.com> Tested-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: <zy.zhengyi@alibaba-inc.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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blk-mq.h
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef INT_BLK_MQ_H
#define INT_BLK_MQ_H
#include "blk-stat.h"
#include "blk-mq-tag.h"
struct blk_mq_tag_set;
/**
* struct blk_mq_ctx - State for a software queue facing the submitting CPUs
*/
struct blk_mq_ctx {
struct {
spinlock_t lock;
struct list_head rq_list;
} ____cacheline_aligned_in_smp;
unsigned int cpu;
unsigned int index_hw;
/* incremented at dispatch time */
unsigned long rq_dispatched[2];
unsigned long rq_merged;
/* incremented at completion time */
unsigned long ____cacheline_aligned_in_smp rq_completed[2];
struct request_queue *queue;
struct kobject kobj;
} ____cacheline_aligned_in_smp;
void blk_mq_freeze_queue(struct request_queue *q);
void blk_mq_free_queue(struct request_queue *q);
int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr);
void blk_mq_wake_waiters(struct request_queue *q);
bool blk_mq_dispatch_rq_list(struct request_queue *, struct list_head *, bool);
void blk_mq_flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list);
bool blk_mq_get_driver_tag(struct request *rq);
struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx,
struct blk_mq_ctx *start);
/*
* Internal helpers for allocating/freeing the request map
*/
void blk_mq_free_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
unsigned int hctx_idx);
void blk_mq_free_rq_map(struct blk_mq_tags *tags);
struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set,
unsigned int hctx_idx,
unsigned int nr_tags,
unsigned int reserved_tags);
int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags,
unsigned int hctx_idx, unsigned int depth);
/*
* Internal helpers for request insertion into sw queues
*/
void __blk_mq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
bool at_head);
void blk_mq_request_bypass_insert(struct request *rq, bool run_queue);
void blk_mq_insert_requests(struct blk_mq_hw_ctx *hctx, struct blk_mq_ctx *ctx,
struct list_head *list);
/* Used by blk_insert_cloned_request() to issue request directly */
blk_status_t blk_mq_request_issue_directly(struct request *rq);
void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx,
struct list_head *list);
/*
* CPU -> queue mappings
*/
extern int blk_mq_hw_queue_to_node(unsigned int *map, unsigned int);
static inline struct blk_mq_hw_ctx *blk_mq_map_queue(struct request_queue *q,
int cpu)
{
return q->queue_hw_ctx[q->mq_map[cpu]];
}
/*
* sysfs helpers
*/
extern void blk_mq_sysfs_init(struct request_queue *q);
extern void blk_mq_sysfs_deinit(struct request_queue *q);
extern int __blk_mq_register_dev(struct device *dev, struct request_queue *q);
extern int blk_mq_sysfs_register(struct request_queue *q);
extern void blk_mq_sysfs_unregister(struct request_queue *q);
extern void blk_mq_hctx_kobj_init(struct blk_mq_hw_ctx *hctx);
void blk_mq_release(struct request_queue *q);
/**
* blk_mq_rq_state() - read the current MQ_RQ_* state of a request
* @rq: target request.
*/
static inline enum mq_rq_state blk_mq_rq_state(struct request *rq)
{
return READ_ONCE(rq->state);
}
static inline struct blk_mq_ctx *__blk_mq_get_ctx(struct request_queue *q,
unsigned int cpu)
{
return per_cpu_ptr(q->queue_ctx, cpu);
}
/*
* This assumes per-cpu software queueing queues. They could be per-node
* as well, for instance. For now this is hardcoded as-is. Note that we don't
* care about preemption, since we know the ctx's are persistent. This does
* mean that we can't rely on ctx always matching the currently running CPU.
*/
static inline struct blk_mq_ctx *blk_mq_get_ctx(struct request_queue *q)
{
return __blk_mq_get_ctx(q, get_cpu());
}
static inline void blk_mq_put_ctx(struct blk_mq_ctx *ctx)
{
put_cpu();
}
struct blk_mq_alloc_data {
/* input parameter */
struct request_queue *q;
blk_mq_req_flags_t flags;
unsigned int shallow_depth;
/* input & output parameter */
struct blk_mq_ctx *ctx;
struct blk_mq_hw_ctx *hctx;
};
static inline struct blk_mq_tags *blk_mq_tags_from_data(struct blk_mq_alloc_data *data)
{
if (data->flags & BLK_MQ_REQ_INTERNAL)
return data->hctx->sched_tags;
return data->hctx->tags;
}
static inline bool blk_mq_hctx_stopped(struct blk_mq_hw_ctx *hctx)
{
return test_bit(BLK_MQ_S_STOPPED, &hctx->state);
}
static inline bool blk_mq_hw_queue_mapped(struct blk_mq_hw_ctx *hctx)
{
return hctx->nr_ctx && hctx->tags;
}
void blk_mq_in_flight(struct request_queue *q, struct hd_struct *part,
unsigned int inflight[2]);
void blk_mq_in_flight_rw(struct request_queue *q, struct hd_struct *part,
unsigned int inflight[2]);
static inline void blk_mq_put_dispatch_budget(struct blk_mq_hw_ctx *hctx)
{
struct request_queue *q = hctx->queue;
if (q->mq_ops->put_budget)
q->mq_ops->put_budget(hctx);
}
static inline bool blk_mq_get_dispatch_budget(struct blk_mq_hw_ctx *hctx)
{
struct request_queue *q = hctx->queue;
if (q->mq_ops->get_budget)
return q->mq_ops->get_budget(hctx);
return true;
}
static inline void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx,
struct request *rq)
{
blk_mq_put_tag(hctx, hctx->tags, rq->mq_ctx, rq->tag);
rq->tag = -1;
if (rq->rq_flags & RQF_MQ_INFLIGHT) {
rq->rq_flags &= ~RQF_MQ_INFLIGHT;
atomic_dec(&hctx->nr_active);
}
}
static inline void blk_mq_put_driver_tag_hctx(struct blk_mq_hw_ctx *hctx,
struct request *rq)
{
if (rq->tag == -1 || rq->internal_tag == -1)
return;
__blk_mq_put_driver_tag(hctx, rq);
}
static inline void blk_mq_put_driver_tag(struct request *rq)
{
struct blk_mq_hw_ctx *hctx;
if (rq->tag == -1 || rq->internal_tag == -1)
return;
hctx = blk_mq_map_queue(rq->q, rq->mq_ctx->cpu);
__blk_mq_put_driver_tag(hctx, rq);
}
static inline void blk_mq_clear_mq_map(struct blk_mq_tag_set *set)
{
int cpu;
for_each_possible_cpu(cpu)
set->mq_map[cpu] = 0;
}
#endif
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