Revision 95a49603707d982b25d17c5b70e220a05556a2f9 authored by Ming Lei on 22 March 2017, 02:14:43 UTC, committed by Jens Axboe on 22 March 2017, 14:03:35 UTC
When iterating busy requests in timeout handler, if the STARTED flag of one request isn't set, that means the request is being processed in block layer or driver, and isn't submitted to hardware yet. In current implementation of blk_mq_check_expired(), if the request queue becomes dying, un-started requests are handled as being completed/freed immediately. This way is wrong, and can cause rq corruption or double allocation[1][2], when doing I/O and removing&resetting NVMe device at the sametime. This patch fixes several issues reported by Yi Zhang. [1]. oops log 1 [ 581.789754] ------------[ cut here ]------------ [ 581.789758] kernel BUG at block/blk-mq.c:374! [ 581.789760] invalid opcode: 0000 [#1] SMP [ 581.789761] Modules linked in: vfat fat ipmi_ssif intel_rapl sb_edac edac_core x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm nvme irqbypass crct10dif_pclmul nvme_core crc32_pclmul ghash_clmulni_intel intel_cstate ipmi_si mei_me ipmi_devintf intel_uncore sg ipmi_msghandler intel_rapl_perf iTCO_wdt mei iTCO_vendor_support mxm_wmi lpc_ich dcdbas shpchp pcspkr acpi_power_meter wmi nfsd auth_rpcgss nfs_acl lockd dm_multipath grace sunrpc ip_tables xfs libcrc32c sd_mod mgag200 i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm ahci libahci crc32c_intel tg3 libata megaraid_sas i2c_core ptp fjes pps_core dm_mirror dm_region_hash dm_log dm_mod [ 581.789796] CPU: 1 PID: 1617 Comm: kworker/1:1H Not tainted 4.10.0.bz1420297+ #4 [ 581.789797] Hardware name: Dell Inc. PowerEdge R730xd/072T6D, BIOS 2.2.5 09/06/2016 [ 581.789804] Workqueue: kblockd blk_mq_timeout_work [ 581.789806] task: ffff8804721c8000 task.stack: ffffc90006ee4000 [ 581.789809] RIP: 0010:blk_mq_end_request+0x58/0x70 [ 581.789810] RSP: 0018:ffffc90006ee7d50 EFLAGS: 00010202 [ 581.789811] RAX: 0000000000000001 RBX: ffff8802e4195340 RCX: ffff88028e2f4b88 [ 581.789812] RDX: 0000000000001000 RSI: 0000000000001000 RDI: 0000000000000000 [ 581.789813] RBP: ffffc90006ee7d60 R08: 0000000000000003 R09: ffff88028e2f4b00 [ 581.789814] R10: 0000000000001000 R11: 0000000000000001 R12: 00000000fffffffb [ 581.789815] R13: ffff88042abe5780 R14: 000000000000002d R15: ffff88046fbdff80 [ 581.789817] FS: 0000000000000000(0000) GS:ffff88047fc00000(0000) knlGS:0000000000000000 [ 581.789818] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 581.789819] CR2: 00007f64f403a008 CR3: 000000014d078000 CR4: 00000000001406e0 [ 581.789820] Call Trace: [ 581.789825] blk_mq_check_expired+0x76/0x80 [ 581.789828] bt_iter+0x45/0x50 [ 581.789830] blk_mq_queue_tag_busy_iter+0xdd/0x1f0 [ 581.789832] ? blk_mq_rq_timed_out+0x70/0x70 [ 581.789833] ? blk_mq_rq_timed_out+0x70/0x70 [ 581.789840] ? __switch_to+0x140/0x450 [ 581.789841] blk_mq_timeout_work+0x88/0x170 [ 581.789845] process_one_work+0x165/0x410 [ 581.789847] worker_thread+0x137/0x4c0 [ 581.789851] kthread+0x101/0x140 [ 581.789853] ? rescuer_thread+0x3b0/0x3b0 [ 581.789855] ? kthread_park+0x90/0x90 [ 581.789860] ret_from_fork+0x2c/0x40 [ 581.789861] Code: 48 85 c0 74 0d 44 89 e6 48 89 df ff d0 5b 41 5c 5d c3 48 8b bb 70 01 00 00 48 85 ff 75 0f 48 89 df e8 7d f0 ff ff 5b 41 5c 5d c3 <0f> 0b e8 71 f0 ff ff 90 eb e9 0f 1f 40 00 66 2e 0f 1f 84 00 00 [ 581.789882] RIP: blk_mq_end_request+0x58/0x70 RSP: ffffc90006ee7d50 [ 581.789889] ---[ end trace bcaf03d9a14a0a70 ]--- [2]. oops log2 [ 6984.857362] BUG: unable to handle kernel NULL pointer dereference at 0000000000000010 [ 6984.857372] IP: nvme_queue_rq+0x6e6/0x8cd [nvme] [ 6984.857373] PGD 0 [ 6984.857374] [ 6984.857376] Oops: 0000 [#1] SMP [ 6984.857379] Modules linked in: ipmi_ssif vfat fat intel_rapl sb_edac edac_core x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel ipmi_si iTCO_wdt iTCO_vendor_support mxm_wmi ipmi_devintf intel_cstate sg dcdbas intel_uncore mei_me intel_rapl_perf mei pcspkr lpc_ich ipmi_msghandler shpchp acpi_power_meter wmi nfsd auth_rpcgss dm_multipath nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c sd_mod mgag200 i2c_algo_bit drm_kms_helper syscopyarea sysfillrect crc32c_intel sysimgblt fb_sys_fops ttm nvme drm nvme_core ahci libahci i2c_core tg3 libata ptp megaraid_sas pps_core fjes dm_mirror dm_region_hash dm_log dm_mod [ 6984.857416] CPU: 7 PID: 1635 Comm: kworker/7:1H Not tainted 4.10.0-2.el7.bz1420297.x86_64 #1 [ 6984.857417] Hardware name: Dell Inc. PowerEdge R730xd/072T6D, BIOS 2.2.5 09/06/2016 [ 6984.857427] Workqueue: kblockd blk_mq_run_work_fn [ 6984.857429] task: ffff880476e3da00 task.stack: ffffc90002e90000 [ 6984.857432] RIP: 0010:nvme_queue_rq+0x6e6/0x8cd [nvme] [ 6984.857433] RSP: 0018:ffffc90002e93c50 EFLAGS: 00010246 [ 6984.857434] RAX: 0000000000000000 RBX: ffff880275646600 RCX: 0000000000001000 [ 6984.857435] RDX: 0000000000000fff RSI: 00000002fba2a000 RDI: ffff8804734e6950 [ 6984.857436] RBP: ffffc90002e93d30 R08: 0000000000002000 R09: 0000000000001000 [ 6984.857437] R10: 0000000000001000 R11: 0000000000000000 R12: ffff8804741d8000 [ 6984.857438] R13: 0000000000000040 R14: ffff880475649f80 R15: ffff8804734e6780 [ 6984.857439] FS: 0000000000000000(0000) GS:ffff88047fcc0000(0000) knlGS:0000000000000000 [ 6984.857440] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 6984.857442] CR2: 0000000000000010 CR3: 0000000001c09000 CR4: 00000000001406e0 [ 6984.857443] Call Trace: [ 6984.857451] ? mempool_free+0x2b/0x80 [ 6984.857455] ? bio_free+0x4e/0x60 [ 6984.857459] blk_mq_dispatch_rq_list+0xf5/0x230 [ 6984.857462] blk_mq_process_rq_list+0x133/0x170 [ 6984.857465] __blk_mq_run_hw_queue+0x8c/0xa0 [ 6984.857467] blk_mq_run_work_fn+0x12/0x20 [ 6984.857473] process_one_work+0x165/0x410 [ 6984.857475] worker_thread+0x137/0x4c0 [ 6984.857478] kthread+0x101/0x140 [ 6984.857480] ? rescuer_thread+0x3b0/0x3b0 [ 6984.857481] ? kthread_park+0x90/0x90 [ 6984.857489] ret_from_fork+0x2c/0x40 [ 6984.857490] Code: 8b bd 70 ff ff ff 89 95 50 ff ff ff 89 8d 58 ff ff ff 44 89 95 60 ff ff ff e8 b7 dd 12 e1 8b 95 50 ff ff ff 48 89 85 68 ff ff ff <4c> 8b 48 10 44 8b 58 18 8b 8d 58 ff ff ff 44 8b 95 60 ff ff ff [ 6984.857511] RIP: nvme_queue_rq+0x6e6/0x8cd [nvme] RSP: ffffc90002e93c50 [ 6984.857512] CR2: 0000000000000010 [ 6984.895359] ---[ end trace 2d7ceb528432bf83 ]--- Cc: stable@vger.kernel.org Reported-by: Yi Zhang <yizhan@redhat.com> Tested-by: Yi Zhang <yizhan@redhat.com> Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
1 parent a457d08
z3fold.c
/*
* z3fold.c
*
* Author: Vitaly Wool <vitaly.wool@konsulko.com>
* Copyright (C) 2016, Sony Mobile Communications Inc.
*
* This implementation is based on zbud written by Seth Jennings.
*
* z3fold is an special purpose allocator for storing compressed pages. It
* can store up to three compressed pages per page which improves the
* compression ratio of zbud while retaining its main concepts (e. g. always
* storing an integral number of objects per page) and simplicity.
* It still has simple and deterministic reclaim properties that make it
* preferable to a higher density approach (with no requirement on integral
* number of object per page) when reclaim is used.
*
* As in zbud, pages are divided into "chunks". The size of the chunks is
* fixed at compile time and is determined by NCHUNKS_ORDER below.
*
* z3fold doesn't export any API and is meant to be used via zpool API.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/atomic.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/preempt.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/zpool.h>
/*****************
* Structures
*****************/
struct z3fold_pool;
struct z3fold_ops {
int (*evict)(struct z3fold_pool *pool, unsigned long handle);
};
enum buddy {
HEADLESS = 0,
FIRST,
MIDDLE,
LAST,
BUDDIES_MAX
};
/*
* struct z3fold_header - z3fold page metadata occupying the first chunk of each
* z3fold page, except for HEADLESS pages
* @buddy: links the z3fold page into the relevant list in the pool
* @page_lock: per-page lock
* @refcount: reference cound for the z3fold page
* @first_chunks: the size of the first buddy in chunks, 0 if free
* @middle_chunks: the size of the middle buddy in chunks, 0 if free
* @last_chunks: the size of the last buddy in chunks, 0 if free
* @first_num: the starting number (for the first handle)
*/
struct z3fold_header {
struct list_head buddy;
spinlock_t page_lock;
struct kref refcount;
unsigned short first_chunks;
unsigned short middle_chunks;
unsigned short last_chunks;
unsigned short start_middle;
unsigned short first_num:2;
};
/*
* NCHUNKS_ORDER determines the internal allocation granularity, effectively
* adjusting internal fragmentation. It also determines the number of
* freelists maintained in each pool. NCHUNKS_ORDER of 6 means that the
* allocation granularity will be in chunks of size PAGE_SIZE/64. Some chunks
* in the beginning of an allocated page are occupied by z3fold header, so
* NCHUNKS will be calculated to 63 (or 62 in case CONFIG_DEBUG_SPINLOCK=y),
* which shows the max number of free chunks in z3fold page, also there will
* be 63, or 62, respectively, freelists per pool.
*/
#define NCHUNKS_ORDER 6
#define CHUNK_SHIFT (PAGE_SHIFT - NCHUNKS_ORDER)
#define CHUNK_SIZE (1 << CHUNK_SHIFT)
#define ZHDR_SIZE_ALIGNED round_up(sizeof(struct z3fold_header), CHUNK_SIZE)
#define ZHDR_CHUNKS (ZHDR_SIZE_ALIGNED >> CHUNK_SHIFT)
#define TOTAL_CHUNKS (PAGE_SIZE >> CHUNK_SHIFT)
#define NCHUNKS ((PAGE_SIZE - ZHDR_SIZE_ALIGNED) >> CHUNK_SHIFT)
#define BUDDY_MASK (0x3)
/**
* struct z3fold_pool - stores metadata for each z3fold pool
* @lock: protects all pool fields and first|last_chunk fields of any
* z3fold page in the pool
* @unbuddied: array of lists tracking z3fold pages that contain 2- buddies;
* the lists each z3fold page is added to depends on the size of
* its free region.
* @lru: list tracking the z3fold pages in LRU order by most recently
* added buddy.
* @pages_nr: number of z3fold pages in the pool.
* @ops: pointer to a structure of user defined operations specified at
* pool creation time.
*
* This structure is allocated at pool creation time and maintains metadata
* pertaining to a particular z3fold pool.
*/
struct z3fold_pool {
spinlock_t lock;
struct list_head unbuddied[NCHUNKS];
struct list_head lru;
atomic64_t pages_nr;
const struct z3fold_ops *ops;
struct zpool *zpool;
const struct zpool_ops *zpool_ops;
};
/*
* Internal z3fold page flags
*/
enum z3fold_page_flags {
PAGE_HEADLESS = 0,
MIDDLE_CHUNK_MAPPED,
};
/*****************
* Helpers
*****************/
/* Converts an allocation size in bytes to size in z3fold chunks */
static int size_to_chunks(size_t size)
{
return (size + CHUNK_SIZE - 1) >> CHUNK_SHIFT;
}
#define for_each_unbuddied_list(_iter, _begin) \
for ((_iter) = (_begin); (_iter) < NCHUNKS; (_iter)++)
/* Initializes the z3fold header of a newly allocated z3fold page */
static struct z3fold_header *init_z3fold_page(struct page *page)
{
struct z3fold_header *zhdr = page_address(page);
INIT_LIST_HEAD(&page->lru);
clear_bit(PAGE_HEADLESS, &page->private);
clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
spin_lock_init(&zhdr->page_lock);
kref_init(&zhdr->refcount);
zhdr->first_chunks = 0;
zhdr->middle_chunks = 0;
zhdr->last_chunks = 0;
zhdr->first_num = 0;
zhdr->start_middle = 0;
INIT_LIST_HEAD(&zhdr->buddy);
return zhdr;
}
/* Resets the struct page fields and frees the page */
static void free_z3fold_page(struct page *page)
{
__free_page(page);
}
static void release_z3fold_page(struct kref *ref)
{
struct z3fold_header *zhdr;
struct page *page;
zhdr = container_of(ref, struct z3fold_header, refcount);
page = virt_to_page(zhdr);
if (!list_empty(&zhdr->buddy))
list_del(&zhdr->buddy);
if (!list_empty(&page->lru))
list_del(&page->lru);
free_z3fold_page(page);
}
/* Lock a z3fold page */
static inline void z3fold_page_lock(struct z3fold_header *zhdr)
{
spin_lock(&zhdr->page_lock);
}
/* Unlock a z3fold page */
static inline void z3fold_page_unlock(struct z3fold_header *zhdr)
{
spin_unlock(&zhdr->page_lock);
}
/*
* Encodes the handle of a particular buddy within a z3fold page
* Pool lock should be held as this function accesses first_num
*/
static unsigned long encode_handle(struct z3fold_header *zhdr, enum buddy bud)
{
unsigned long handle;
handle = (unsigned long)zhdr;
if (bud != HEADLESS)
handle += (bud + zhdr->first_num) & BUDDY_MASK;
return handle;
}
/* Returns the z3fold page where a given handle is stored */
static struct z3fold_header *handle_to_z3fold_header(unsigned long handle)
{
return (struct z3fold_header *)(handle & PAGE_MASK);
}
/*
* (handle & BUDDY_MASK) < zhdr->first_num is possible in encode_handle
* but that doesn't matter. because the masking will result in the
* correct buddy number.
*/
static enum buddy handle_to_buddy(unsigned long handle)
{
struct z3fold_header *zhdr = handle_to_z3fold_header(handle);
return (handle - zhdr->first_num) & BUDDY_MASK;
}
/*
* Returns the number of free chunks in a z3fold page.
* NB: can't be used with HEADLESS pages.
*/
static int num_free_chunks(struct z3fold_header *zhdr)
{
int nfree;
/*
* If there is a middle object, pick up the bigger free space
* either before or after it. Otherwise just subtract the number
* of chunks occupied by the first and the last objects.
*/
if (zhdr->middle_chunks != 0) {
int nfree_before = zhdr->first_chunks ?
0 : zhdr->start_middle - ZHDR_CHUNKS;
int nfree_after = zhdr->last_chunks ?
0 : TOTAL_CHUNKS -
(zhdr->start_middle + zhdr->middle_chunks);
nfree = max(nfree_before, nfree_after);
} else
nfree = NCHUNKS - zhdr->first_chunks - zhdr->last_chunks;
return nfree;
}
/*****************
* API Functions
*****************/
/**
* z3fold_create_pool() - create a new z3fold pool
* @gfp: gfp flags when allocating the z3fold pool structure
* @ops: user-defined operations for the z3fold pool
*
* Return: pointer to the new z3fold pool or NULL if the metadata allocation
* failed.
*/
static struct z3fold_pool *z3fold_create_pool(gfp_t gfp,
const struct z3fold_ops *ops)
{
struct z3fold_pool *pool;
int i;
pool = kzalloc(sizeof(struct z3fold_pool), gfp);
if (!pool)
return NULL;
spin_lock_init(&pool->lock);
for_each_unbuddied_list(i, 0)
INIT_LIST_HEAD(&pool->unbuddied[i]);
INIT_LIST_HEAD(&pool->lru);
atomic64_set(&pool->pages_nr, 0);
pool->ops = ops;
return pool;
}
/**
* z3fold_destroy_pool() - destroys an existing z3fold pool
* @pool: the z3fold pool to be destroyed
*
* The pool should be emptied before this function is called.
*/
static void z3fold_destroy_pool(struct z3fold_pool *pool)
{
kfree(pool);
}
static inline void *mchunk_memmove(struct z3fold_header *zhdr,
unsigned short dst_chunk)
{
void *beg = zhdr;
return memmove(beg + (dst_chunk << CHUNK_SHIFT),
beg + (zhdr->start_middle << CHUNK_SHIFT),
zhdr->middle_chunks << CHUNK_SHIFT);
}
#define BIG_CHUNK_GAP 3
/* Has to be called with lock held */
static int z3fold_compact_page(struct z3fold_header *zhdr)
{
struct page *page = virt_to_page(zhdr);
if (test_bit(MIDDLE_CHUNK_MAPPED, &page->private))
return 0; /* can't move middle chunk, it's used */
if (zhdr->middle_chunks == 0)
return 0; /* nothing to compact */
if (zhdr->first_chunks == 0 && zhdr->last_chunks == 0) {
/* move to the beginning */
mchunk_memmove(zhdr, ZHDR_CHUNKS);
zhdr->first_chunks = zhdr->middle_chunks;
zhdr->middle_chunks = 0;
zhdr->start_middle = 0;
zhdr->first_num++;
return 1;
}
/*
* moving data is expensive, so let's only do that if
* there's substantial gain (at least BIG_CHUNK_GAP chunks)
*/
if (zhdr->first_chunks != 0 && zhdr->last_chunks == 0 &&
zhdr->start_middle - (zhdr->first_chunks + ZHDR_CHUNKS) >=
BIG_CHUNK_GAP) {
mchunk_memmove(zhdr, zhdr->first_chunks + ZHDR_CHUNKS);
zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
return 1;
} else if (zhdr->last_chunks != 0 && zhdr->first_chunks == 0 &&
TOTAL_CHUNKS - (zhdr->last_chunks + zhdr->start_middle
+ zhdr->middle_chunks) >=
BIG_CHUNK_GAP) {
unsigned short new_start = TOTAL_CHUNKS - zhdr->last_chunks -
zhdr->middle_chunks;
mchunk_memmove(zhdr, new_start);
zhdr->start_middle = new_start;
return 1;
}
return 0;
}
/**
* z3fold_alloc() - allocates a region of a given size
* @pool: z3fold pool from which to allocate
* @size: size in bytes of the desired allocation
* @gfp: gfp flags used if the pool needs to grow
* @handle: handle of the new allocation
*
* This function will attempt to find a free region in the pool large enough to
* satisfy the allocation request. A search of the unbuddied lists is
* performed first. If no suitable free region is found, then a new page is
* allocated and added to the pool to satisfy the request.
*
* gfp should not set __GFP_HIGHMEM as highmem pages cannot be used
* as z3fold pool pages.
*
* Return: 0 if success and handle is set, otherwise -EINVAL if the size or
* gfp arguments are invalid or -ENOMEM if the pool was unable to allocate
* a new page.
*/
static int z3fold_alloc(struct z3fold_pool *pool, size_t size, gfp_t gfp,
unsigned long *handle)
{
int chunks = 0, i, freechunks;
struct z3fold_header *zhdr = NULL;
enum buddy bud;
struct page *page;
if (!size || (gfp & __GFP_HIGHMEM))
return -EINVAL;
if (size > PAGE_SIZE)
return -ENOSPC;
if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE)
bud = HEADLESS;
else {
chunks = size_to_chunks(size);
/* First, try to find an unbuddied z3fold page. */
zhdr = NULL;
for_each_unbuddied_list(i, chunks) {
spin_lock(&pool->lock);
zhdr = list_first_entry_or_null(&pool->unbuddied[i],
struct z3fold_header, buddy);
if (!zhdr) {
spin_unlock(&pool->lock);
continue;
}
kref_get(&zhdr->refcount);
list_del_init(&zhdr->buddy);
spin_unlock(&pool->lock);
page = virt_to_page(zhdr);
z3fold_page_lock(zhdr);
if (zhdr->first_chunks == 0) {
if (zhdr->middle_chunks != 0 &&
chunks >= zhdr->start_middle)
bud = LAST;
else
bud = FIRST;
} else if (zhdr->last_chunks == 0)
bud = LAST;
else if (zhdr->middle_chunks == 0)
bud = MIDDLE;
else {
z3fold_page_unlock(zhdr);
spin_lock(&pool->lock);
if (kref_put(&zhdr->refcount,
release_z3fold_page))
atomic64_dec(&pool->pages_nr);
spin_unlock(&pool->lock);
pr_err("No free chunks in unbuddied\n");
WARN_ON(1);
continue;
}
goto found;
}
bud = FIRST;
}
/* Couldn't find unbuddied z3fold page, create new one */
page = alloc_page(gfp);
if (!page)
return -ENOMEM;
atomic64_inc(&pool->pages_nr);
zhdr = init_z3fold_page(page);
if (bud == HEADLESS) {
set_bit(PAGE_HEADLESS, &page->private);
spin_lock(&pool->lock);
goto headless;
}
z3fold_page_lock(zhdr);
found:
if (bud == FIRST)
zhdr->first_chunks = chunks;
else if (bud == LAST)
zhdr->last_chunks = chunks;
else {
zhdr->middle_chunks = chunks;
zhdr->start_middle = zhdr->first_chunks + ZHDR_CHUNKS;
}
spin_lock(&pool->lock);
if (zhdr->first_chunks == 0 || zhdr->last_chunks == 0 ||
zhdr->middle_chunks == 0) {
/* Add to unbuddied list */
freechunks = num_free_chunks(zhdr);
list_add(&zhdr->buddy, &pool->unbuddied[freechunks]);
}
headless:
/* Add/move z3fold page to beginning of LRU */
if (!list_empty(&page->lru))
list_del(&page->lru);
list_add(&page->lru, &pool->lru);
*handle = encode_handle(zhdr, bud);
spin_unlock(&pool->lock);
if (bud != HEADLESS)
z3fold_page_unlock(zhdr);
return 0;
}
/**
* z3fold_free() - frees the allocation associated with the given handle
* @pool: pool in which the allocation resided
* @handle: handle associated with the allocation returned by z3fold_alloc()
*
* In the case that the z3fold page in which the allocation resides is under
* reclaim, as indicated by the PG_reclaim flag being set, this function
* only sets the first|last_chunks to 0. The page is actually freed
* once both buddies are evicted (see z3fold_reclaim_page() below).
*/
static void z3fold_free(struct z3fold_pool *pool, unsigned long handle)
{
struct z3fold_header *zhdr;
int freechunks;
struct page *page;
enum buddy bud;
zhdr = handle_to_z3fold_header(handle);
page = virt_to_page(zhdr);
if (test_bit(PAGE_HEADLESS, &page->private)) {
/* HEADLESS page stored */
bud = HEADLESS;
} else {
z3fold_page_lock(zhdr);
bud = handle_to_buddy(handle);
switch (bud) {
case FIRST:
zhdr->first_chunks = 0;
break;
case MIDDLE:
zhdr->middle_chunks = 0;
zhdr->start_middle = 0;
break;
case LAST:
zhdr->last_chunks = 0;
break;
default:
pr_err("%s: unknown bud %d\n", __func__, bud);
WARN_ON(1);
z3fold_page_unlock(zhdr);
return;
}
}
if (bud == HEADLESS) {
spin_lock(&pool->lock);
list_del(&page->lru);
spin_unlock(&pool->lock);
free_z3fold_page(page);
atomic64_dec(&pool->pages_nr);
} else {
if (zhdr->first_chunks != 0 || zhdr->middle_chunks != 0 ||
zhdr->last_chunks != 0) {
z3fold_compact_page(zhdr);
/* Add to the unbuddied list */
spin_lock(&pool->lock);
if (!list_empty(&zhdr->buddy))
list_del(&zhdr->buddy);
freechunks = num_free_chunks(zhdr);
list_add(&zhdr->buddy, &pool->unbuddied[freechunks]);
spin_unlock(&pool->lock);
}
z3fold_page_unlock(zhdr);
spin_lock(&pool->lock);
if (kref_put(&zhdr->refcount, release_z3fold_page))
atomic64_dec(&pool->pages_nr);
spin_unlock(&pool->lock);
}
}
/**
* z3fold_reclaim_page() - evicts allocations from a pool page and frees it
* @pool: pool from which a page will attempt to be evicted
* @retires: number of pages on the LRU list for which eviction will
* be attempted before failing
*
* z3fold reclaim is different from normal system reclaim in that it is done
* from the bottom, up. This is because only the bottom layer, z3fold, has
* information on how the allocations are organized within each z3fold page.
* This has the potential to create interesting locking situations between
* z3fold and the user, however.
*
* To avoid these, this is how z3fold_reclaim_page() should be called:
* The user detects a page should be reclaimed and calls z3fold_reclaim_page().
* z3fold_reclaim_page() will remove a z3fold page from the pool LRU list and
* call the user-defined eviction handler with the pool and handle as
* arguments.
*
* If the handle can not be evicted, the eviction handler should return
* non-zero. z3fold_reclaim_page() will add the z3fold page back to the
* appropriate list and try the next z3fold page on the LRU up to
* a user defined number of retries.
*
* If the handle is successfully evicted, the eviction handler should
* return 0 _and_ should have called z3fold_free() on the handle. z3fold_free()
* contains logic to delay freeing the page if the page is under reclaim,
* as indicated by the setting of the PG_reclaim flag on the underlying page.
*
* If all buddies in the z3fold page are successfully evicted, then the
* z3fold page can be freed.
*
* Returns: 0 if page is successfully freed, otherwise -EINVAL if there are
* no pages to evict or an eviction handler is not registered, -EAGAIN if
* the retry limit was hit.
*/
static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries)
{
int i, ret = 0, freechunks;
struct z3fold_header *zhdr;
struct page *page;
unsigned long first_handle = 0, middle_handle = 0, last_handle = 0;
spin_lock(&pool->lock);
if (!pool->ops || !pool->ops->evict || retries == 0) {
spin_unlock(&pool->lock);
return -EINVAL;
}
for (i = 0; i < retries; i++) {
if (list_empty(&pool->lru)) {
spin_unlock(&pool->lock);
return -EINVAL;
}
page = list_last_entry(&pool->lru, struct page, lru);
list_del_init(&page->lru);
zhdr = page_address(page);
if (!test_bit(PAGE_HEADLESS, &page->private)) {
if (!list_empty(&zhdr->buddy))
list_del_init(&zhdr->buddy);
kref_get(&zhdr->refcount);
spin_unlock(&pool->lock);
z3fold_page_lock(zhdr);
/*
* We need encode the handles before unlocking, since
* we can race with free that will set
* (first|last)_chunks to 0
*/
first_handle = 0;
last_handle = 0;
middle_handle = 0;
if (zhdr->first_chunks)
first_handle = encode_handle(zhdr, FIRST);
if (zhdr->middle_chunks)
middle_handle = encode_handle(zhdr, MIDDLE);
if (zhdr->last_chunks)
last_handle = encode_handle(zhdr, LAST);
z3fold_page_unlock(zhdr);
} else {
first_handle = encode_handle(zhdr, HEADLESS);
last_handle = middle_handle = 0;
spin_unlock(&pool->lock);
}
/* Issue the eviction callback(s) */
if (middle_handle) {
ret = pool->ops->evict(pool, middle_handle);
if (ret)
goto next;
}
if (first_handle) {
ret = pool->ops->evict(pool, first_handle);
if (ret)
goto next;
}
if (last_handle) {
ret = pool->ops->evict(pool, last_handle);
if (ret)
goto next;
}
next:
if (test_bit(PAGE_HEADLESS, &page->private)) {
if (ret == 0) {
free_z3fold_page(page);
return 0;
} else {
spin_lock(&pool->lock);
}
} else {
z3fold_page_lock(zhdr);
if ((zhdr->first_chunks || zhdr->last_chunks ||
zhdr->middle_chunks) &&
!(zhdr->first_chunks && zhdr->last_chunks &&
zhdr->middle_chunks)) {
z3fold_compact_page(zhdr);
/* add to unbuddied list */
spin_lock(&pool->lock);
freechunks = num_free_chunks(zhdr);
list_add(&zhdr->buddy,
&pool->unbuddied[freechunks]);
spin_unlock(&pool->lock);
}
z3fold_page_unlock(zhdr);
spin_lock(&pool->lock);
if (kref_put(&zhdr->refcount, release_z3fold_page)) {
atomic64_dec(&pool->pages_nr);
return 0;
}
}
/*
* Add to the beginning of LRU.
* Pool lock has to be kept here to ensure the page has
* not already been released
*/
list_add(&page->lru, &pool->lru);
}
spin_unlock(&pool->lock);
return -EAGAIN;
}
/**
* z3fold_map() - maps the allocation associated with the given handle
* @pool: pool in which the allocation resides
* @handle: handle associated with the allocation to be mapped
*
* Extracts the buddy number from handle and constructs the pointer to the
* correct starting chunk within the page.
*
* Returns: a pointer to the mapped allocation
*/
static void *z3fold_map(struct z3fold_pool *pool, unsigned long handle)
{
struct z3fold_header *zhdr;
struct page *page;
void *addr;
enum buddy buddy;
zhdr = handle_to_z3fold_header(handle);
addr = zhdr;
page = virt_to_page(zhdr);
if (test_bit(PAGE_HEADLESS, &page->private))
goto out;
z3fold_page_lock(zhdr);
buddy = handle_to_buddy(handle);
switch (buddy) {
case FIRST:
addr += ZHDR_SIZE_ALIGNED;
break;
case MIDDLE:
addr += zhdr->start_middle << CHUNK_SHIFT;
set_bit(MIDDLE_CHUNK_MAPPED, &page->private);
break;
case LAST:
addr += PAGE_SIZE - (zhdr->last_chunks << CHUNK_SHIFT);
break;
default:
pr_err("unknown buddy id %d\n", buddy);
WARN_ON(1);
addr = NULL;
break;
}
z3fold_page_unlock(zhdr);
out:
return addr;
}
/**
* z3fold_unmap() - unmaps the allocation associated with the given handle
* @pool: pool in which the allocation resides
* @handle: handle associated with the allocation to be unmapped
*/
static void z3fold_unmap(struct z3fold_pool *pool, unsigned long handle)
{
struct z3fold_header *zhdr;
struct page *page;
enum buddy buddy;
zhdr = handle_to_z3fold_header(handle);
page = virt_to_page(zhdr);
if (test_bit(PAGE_HEADLESS, &page->private))
return;
z3fold_page_lock(zhdr);
buddy = handle_to_buddy(handle);
if (buddy == MIDDLE)
clear_bit(MIDDLE_CHUNK_MAPPED, &page->private);
z3fold_page_unlock(zhdr);
}
/**
* z3fold_get_pool_size() - gets the z3fold pool size in pages
* @pool: pool whose size is being queried
*
* Returns: size in pages of the given pool.
*/
static u64 z3fold_get_pool_size(struct z3fold_pool *pool)
{
return atomic64_read(&pool->pages_nr);
}
/*****************
* zpool
****************/
static int z3fold_zpool_evict(struct z3fold_pool *pool, unsigned long handle)
{
if (pool->zpool && pool->zpool_ops && pool->zpool_ops->evict)
return pool->zpool_ops->evict(pool->zpool, handle);
else
return -ENOENT;
}
static const struct z3fold_ops z3fold_zpool_ops = {
.evict = z3fold_zpool_evict
};
static void *z3fold_zpool_create(const char *name, gfp_t gfp,
const struct zpool_ops *zpool_ops,
struct zpool *zpool)
{
struct z3fold_pool *pool;
pool = z3fold_create_pool(gfp, zpool_ops ? &z3fold_zpool_ops : NULL);
if (pool) {
pool->zpool = zpool;
pool->zpool_ops = zpool_ops;
}
return pool;
}
static void z3fold_zpool_destroy(void *pool)
{
z3fold_destroy_pool(pool);
}
static int z3fold_zpool_malloc(void *pool, size_t size, gfp_t gfp,
unsigned long *handle)
{
return z3fold_alloc(pool, size, gfp, handle);
}
static void z3fold_zpool_free(void *pool, unsigned long handle)
{
z3fold_free(pool, handle);
}
static int z3fold_zpool_shrink(void *pool, unsigned int pages,
unsigned int *reclaimed)
{
unsigned int total = 0;
int ret = -EINVAL;
while (total < pages) {
ret = z3fold_reclaim_page(pool, 8);
if (ret < 0)
break;
total++;
}
if (reclaimed)
*reclaimed = total;
return ret;
}
static void *z3fold_zpool_map(void *pool, unsigned long handle,
enum zpool_mapmode mm)
{
return z3fold_map(pool, handle);
}
static void z3fold_zpool_unmap(void *pool, unsigned long handle)
{
z3fold_unmap(pool, handle);
}
static u64 z3fold_zpool_total_size(void *pool)
{
return z3fold_get_pool_size(pool) * PAGE_SIZE;
}
static struct zpool_driver z3fold_zpool_driver = {
.type = "z3fold",
.owner = THIS_MODULE,
.create = z3fold_zpool_create,
.destroy = z3fold_zpool_destroy,
.malloc = z3fold_zpool_malloc,
.free = z3fold_zpool_free,
.shrink = z3fold_zpool_shrink,
.map = z3fold_zpool_map,
.unmap = z3fold_zpool_unmap,
.total_size = z3fold_zpool_total_size,
};
MODULE_ALIAS("zpool-z3fold");
static int __init init_z3fold(void)
{
/* Make sure the z3fold header is not larger than the page size */
BUILD_BUG_ON(ZHDR_SIZE_ALIGNED > PAGE_SIZE);
zpool_register_driver(&z3fold_zpool_driver);
return 0;
}
static void __exit exit_z3fold(void)
{
zpool_unregister_driver(&z3fold_zpool_driver);
}
module_init(init_z3fold);
module_exit(exit_z3fold);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Vitaly Wool <vitalywool@gmail.com>");
MODULE_DESCRIPTION("3-Fold Allocator for Compressed Pages");
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