![Kees Cook](/assets/img/avatar_default.png)
The kvzalloc() function has a 2-factor argument form, kvcalloc(). This patch replaces cases of: kvzalloc(a * b, gfp) with: kvcalloc(a * b, gfp) as well as handling cases of: kvzalloc(a * b * c, gfp) with: kvzalloc(array3_size(a, b, c), gfp) as it's slightly less ugly than: kvcalloc(array_size(a, b), c, gfp) This does, however, attempt to ignore constant size factors like: kvzalloc(4 * 1024, gfp) though any constants defined via macros get caught up in the conversion. Any factors with a sizeof() of "unsigned char", "char", and "u8" were dropped, since they're redundant. The Coccinelle script used for this was: // Fix redundant parens around sizeof(). @@ type TYPE; expression THING, E; @@ ( kvzalloc( - (sizeof(TYPE)) * E + sizeof(TYPE) * E , ...) | kvzalloc( - (sizeof(THING)) * E + sizeof(THING) * E , ...) ) // Drop single-byte sizes and redundant parens. @@ expression COUNT; typedef u8; typedef __u8; @@ ( kvzalloc( - sizeof(u8) * (COUNT) + COUNT , ...) | kvzalloc( - sizeof(__u8) * (COUNT) + COUNT , ...) | kvzalloc( - sizeof(char) * (COUNT) + COUNT , ...) | kvzalloc( - sizeof(unsigned char) * (COUNT) + COUNT , ...) | kvzalloc( - sizeof(u8) * COUNT + COUNT , ...) | kvzalloc( - sizeof(__u8) * COUNT + COUNT , ...) | kvzalloc( - sizeof(char) * COUNT + COUNT , ...) | kvzalloc( - sizeof(unsigned char) * COUNT + COUNT , ...) ) // 2-factor product with sizeof(type/expression) and identifier or constant. @@ type TYPE; expression THING; identifier COUNT_ID; constant COUNT_CONST; @@ ( - kvzalloc + kvcalloc ( - sizeof(TYPE) * (COUNT_ID) + COUNT_ID, sizeof(TYPE) , ...) | - kvzalloc + kvcalloc ( - sizeof(TYPE) * COUNT_ID + COUNT_ID, sizeof(TYPE) , ...) | - kvzalloc + kvcalloc ( - sizeof(TYPE) * (COUNT_CONST) + COUNT_CONST, sizeof(TYPE) , ...) | - kvzalloc + kvcalloc ( - sizeof(TYPE) * COUNT_CONST + COUNT_CONST, sizeof(TYPE) , ...) | - kvzalloc + kvcalloc ( - sizeof(THING) * (COUNT_ID) + COUNT_ID, sizeof(THING) , ...) | - kvzalloc + kvcalloc ( - sizeof(THING) * COUNT_ID + COUNT_ID, sizeof(THING) , ...) | - kvzalloc + kvcalloc ( - sizeof(THING) * (COUNT_CONST) + COUNT_CONST, sizeof(THING) , ...) | - kvzalloc + kvcalloc ( - sizeof(THING) * COUNT_CONST + COUNT_CONST, sizeof(THING) , ...) ) // 2-factor product, only identifiers. @@ identifier SIZE, COUNT; @@ - kvzalloc + kvcalloc ( - SIZE * COUNT + COUNT, SIZE , ...) // 3-factor product with 1 sizeof(type) or sizeof(expression), with // redundant parens removed. @@ expression THING; identifier STRIDE, COUNT; type TYPE; @@ ( kvzalloc( - sizeof(TYPE) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kvzalloc( - sizeof(TYPE) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kvzalloc( - sizeof(TYPE) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kvzalloc( - sizeof(TYPE) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kvzalloc( - sizeof(THING) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kvzalloc( - sizeof(THING) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kvzalloc( - sizeof(THING) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kvzalloc( - sizeof(THING) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) ) // 3-factor product with 2 sizeof(variable), with redundant parens removed. @@ expression THING1, THING2; identifier COUNT; type TYPE1, TYPE2; @@ ( kvzalloc( - sizeof(TYPE1) * sizeof(TYPE2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kvzalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kvzalloc( - sizeof(THING1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kvzalloc( - sizeof(THING1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kvzalloc( - sizeof(TYPE1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) | kvzalloc( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) ) // 3-factor product, only identifiers, with redundant parens removed. @@ identifier STRIDE, SIZE, COUNT; @@ ( kvzalloc( - (COUNT) * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kvzalloc( - COUNT * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kvzalloc( - COUNT * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kvzalloc( - (COUNT) * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kvzalloc( - COUNT * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kvzalloc( - (COUNT) * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kvzalloc( - (COUNT) * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kvzalloc( - COUNT * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) ) // Any remaining multi-factor products, first at least 3-factor products, // when they're not all constants... @@ expression E1, E2, E3; constant C1, C2, C3; @@ ( kvzalloc(C1 * C2 * C3, ...) | kvzalloc( - (E1) * E2 * E3 + array3_size(E1, E2, E3) , ...) | kvzalloc( - (E1) * (E2) * E3 + array3_size(E1, E2, E3) , ...) | kvzalloc( - (E1) * (E2) * (E3) + array3_size(E1, E2, E3) , ...) | kvzalloc( - E1 * E2 * E3 + array3_size(E1, E2, E3) , ...) ) // And then all remaining 2 factors products when they're not all constants, // keeping sizeof() as the second factor argument. @@ expression THING, E1, E2; type TYPE; constant C1, C2, C3; @@ ( kvzalloc(sizeof(THING) * C2, ...) | kvzalloc(sizeof(TYPE) * C2, ...) | kvzalloc(C1 * C2 * C3, ...) | kvzalloc(C1 * C2, ...) | - kvzalloc + kvcalloc ( - sizeof(TYPE) * (E2) + E2, sizeof(TYPE) , ...) | - kvzalloc + kvcalloc ( - sizeof(TYPE) * E2 + E2, sizeof(TYPE) , ...) | - kvzalloc + kvcalloc ( - sizeof(THING) * (E2) + E2, sizeof(THING) , ...) | - kvzalloc + kvcalloc ( - sizeof(THING) * E2 + E2, sizeof(THING) , ...) | - kvzalloc + kvcalloc ( - (E1) * E2 + E1, E2 , ...) | - kvzalloc + kvcalloc ( - (E1) * (E2) + E1, E2 , ...) | - kvzalloc + kvcalloc ( - E1 * E2 + E1, E2 , ...) ) Signed-off-by: Kees Cook <keescook@chromium.org>
361 lines
9.4 KiB
C
361 lines
9.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Manage cache of swap slots to be used for and returned from
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* swap.
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*
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* Copyright(c) 2016 Intel Corporation.
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*
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* Author: Tim Chen <tim.c.chen@linux.intel.com>
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*
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* We allocate the swap slots from the global pool and put
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* it into local per cpu caches. This has the advantage
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* of no needing to acquire the swap_info lock every time
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* we need a new slot.
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*
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* There is also opportunity to simply return the slot
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* to local caches without needing to acquire swap_info
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* lock. We do not reuse the returned slots directly but
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* move them back to the global pool in a batch. This
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* allows the slots to coaellesce and reduce fragmentation.
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*
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* The swap entry allocated is marked with SWAP_HAS_CACHE
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* flag in map_count that prevents it from being allocated
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* again from the global pool.
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*
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* The swap slots cache is protected by a mutex instead of
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* a spin lock as when we search for slots with scan_swap_map,
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* we can possibly sleep.
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*/
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#include <linux/swap_slots.h>
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#include <linux/cpu.h>
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#include <linux/cpumask.h>
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#include <linux/vmalloc.h>
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#include <linux/mutex.h>
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#include <linux/mm.h>
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static DEFINE_PER_CPU(struct swap_slots_cache, swp_slots);
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static bool swap_slot_cache_active;
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bool swap_slot_cache_enabled;
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static bool swap_slot_cache_initialized;
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DEFINE_MUTEX(swap_slots_cache_mutex);
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/* Serialize swap slots cache enable/disable operations */
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DEFINE_MUTEX(swap_slots_cache_enable_mutex);
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static void __drain_swap_slots_cache(unsigned int type);
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static void deactivate_swap_slots_cache(void);
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static void reactivate_swap_slots_cache(void);
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#define use_swap_slot_cache (swap_slot_cache_active && \
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swap_slot_cache_enabled && swap_slot_cache_initialized)
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#define SLOTS_CACHE 0x1
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#define SLOTS_CACHE_RET 0x2
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static void deactivate_swap_slots_cache(void)
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{
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mutex_lock(&swap_slots_cache_mutex);
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swap_slot_cache_active = false;
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__drain_swap_slots_cache(SLOTS_CACHE|SLOTS_CACHE_RET);
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mutex_unlock(&swap_slots_cache_mutex);
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}
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static void reactivate_swap_slots_cache(void)
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{
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mutex_lock(&swap_slots_cache_mutex);
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swap_slot_cache_active = true;
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mutex_unlock(&swap_slots_cache_mutex);
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}
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/* Must not be called with cpu hot plug lock */
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void disable_swap_slots_cache_lock(void)
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{
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mutex_lock(&swap_slots_cache_enable_mutex);
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swap_slot_cache_enabled = false;
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if (swap_slot_cache_initialized) {
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/* serialize with cpu hotplug operations */
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get_online_cpus();
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__drain_swap_slots_cache(SLOTS_CACHE|SLOTS_CACHE_RET);
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put_online_cpus();
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}
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}
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static void __reenable_swap_slots_cache(void)
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{
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swap_slot_cache_enabled = has_usable_swap();
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}
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void reenable_swap_slots_cache_unlock(void)
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{
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__reenable_swap_slots_cache();
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mutex_unlock(&swap_slots_cache_enable_mutex);
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}
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static bool check_cache_active(void)
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{
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long pages;
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if (!swap_slot_cache_enabled || !swap_slot_cache_initialized)
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return false;
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pages = get_nr_swap_pages();
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if (!swap_slot_cache_active) {
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if (pages > num_online_cpus() *
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THRESHOLD_ACTIVATE_SWAP_SLOTS_CACHE)
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reactivate_swap_slots_cache();
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goto out;
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}
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/* if global pool of slot caches too low, deactivate cache */
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if (pages < num_online_cpus() * THRESHOLD_DEACTIVATE_SWAP_SLOTS_CACHE)
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deactivate_swap_slots_cache();
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out:
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return swap_slot_cache_active;
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}
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static int alloc_swap_slot_cache(unsigned int cpu)
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{
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struct swap_slots_cache *cache;
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swp_entry_t *slots, *slots_ret;
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/*
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* Do allocation outside swap_slots_cache_mutex
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* as kvzalloc could trigger reclaim and get_swap_page,
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* which can lock swap_slots_cache_mutex.
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*/
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slots = kvcalloc(SWAP_SLOTS_CACHE_SIZE, sizeof(swp_entry_t),
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GFP_KERNEL);
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if (!slots)
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return -ENOMEM;
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slots_ret = kvcalloc(SWAP_SLOTS_CACHE_SIZE, sizeof(swp_entry_t),
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GFP_KERNEL);
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if (!slots_ret) {
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kvfree(slots);
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return -ENOMEM;
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}
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mutex_lock(&swap_slots_cache_mutex);
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cache = &per_cpu(swp_slots, cpu);
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if (cache->slots || cache->slots_ret)
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/* cache already allocated */
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goto out;
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if (!cache->lock_initialized) {
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mutex_init(&cache->alloc_lock);
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spin_lock_init(&cache->free_lock);
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cache->lock_initialized = true;
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}
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cache->nr = 0;
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cache->cur = 0;
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cache->n_ret = 0;
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/*
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* We initialized alloc_lock and free_lock earlier. We use
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* !cache->slots or !cache->slots_ret to know if it is safe to acquire
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* the corresponding lock and use the cache. Memory barrier below
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* ensures the assumption.
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*/
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mb();
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cache->slots = slots;
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slots = NULL;
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cache->slots_ret = slots_ret;
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slots_ret = NULL;
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out:
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mutex_unlock(&swap_slots_cache_mutex);
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if (slots)
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kvfree(slots);
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if (slots_ret)
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kvfree(slots_ret);
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return 0;
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}
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static void drain_slots_cache_cpu(unsigned int cpu, unsigned int type,
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bool free_slots)
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{
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struct swap_slots_cache *cache;
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swp_entry_t *slots = NULL;
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cache = &per_cpu(swp_slots, cpu);
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if ((type & SLOTS_CACHE) && cache->slots) {
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mutex_lock(&cache->alloc_lock);
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swapcache_free_entries(cache->slots + cache->cur, cache->nr);
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cache->cur = 0;
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cache->nr = 0;
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if (free_slots && cache->slots) {
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kvfree(cache->slots);
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cache->slots = NULL;
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}
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mutex_unlock(&cache->alloc_lock);
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}
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if ((type & SLOTS_CACHE_RET) && cache->slots_ret) {
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spin_lock_irq(&cache->free_lock);
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swapcache_free_entries(cache->slots_ret, cache->n_ret);
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cache->n_ret = 0;
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if (free_slots && cache->slots_ret) {
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slots = cache->slots_ret;
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cache->slots_ret = NULL;
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}
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spin_unlock_irq(&cache->free_lock);
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if (slots)
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kvfree(slots);
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}
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}
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static void __drain_swap_slots_cache(unsigned int type)
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{
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unsigned int cpu;
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/*
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* This function is called during
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* 1) swapoff, when we have to make sure no
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* left over slots are in cache when we remove
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* a swap device;
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* 2) disabling of swap slot cache, when we run low
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* on swap slots when allocating memory and need
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* to return swap slots to global pool.
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*
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* We cannot acquire cpu hot plug lock here as
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* this function can be invoked in the cpu
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* hot plug path:
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* cpu_up -> lock cpu_hotplug -> cpu hotplug state callback
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* -> memory allocation -> direct reclaim -> get_swap_page
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* -> drain_swap_slots_cache
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*
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* Hence the loop over current online cpu below could miss cpu that
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* is being brought online but not yet marked as online.
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* That is okay as we do not schedule and run anything on a
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* cpu before it has been marked online. Hence, we will not
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* fill any swap slots in slots cache of such cpu.
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* There are no slots on such cpu that need to be drained.
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*/
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for_each_online_cpu(cpu)
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drain_slots_cache_cpu(cpu, type, false);
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}
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static int free_slot_cache(unsigned int cpu)
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{
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mutex_lock(&swap_slots_cache_mutex);
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drain_slots_cache_cpu(cpu, SLOTS_CACHE | SLOTS_CACHE_RET, true);
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mutex_unlock(&swap_slots_cache_mutex);
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return 0;
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}
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int enable_swap_slots_cache(void)
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{
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int ret = 0;
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mutex_lock(&swap_slots_cache_enable_mutex);
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if (swap_slot_cache_initialized) {
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__reenable_swap_slots_cache();
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goto out_unlock;
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}
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ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "swap_slots_cache",
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alloc_swap_slot_cache, free_slot_cache);
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if (WARN_ONCE(ret < 0, "Cache allocation failed (%s), operating "
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"without swap slots cache.\n", __func__))
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goto out_unlock;
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swap_slot_cache_initialized = true;
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__reenable_swap_slots_cache();
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out_unlock:
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mutex_unlock(&swap_slots_cache_enable_mutex);
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return 0;
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}
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/* called with swap slot cache's alloc lock held */
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static int refill_swap_slots_cache(struct swap_slots_cache *cache)
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{
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if (!use_swap_slot_cache || cache->nr)
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return 0;
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cache->cur = 0;
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if (swap_slot_cache_active)
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cache->nr = get_swap_pages(SWAP_SLOTS_CACHE_SIZE, false,
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cache->slots);
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return cache->nr;
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}
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int free_swap_slot(swp_entry_t entry)
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{
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struct swap_slots_cache *cache;
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cache = raw_cpu_ptr(&swp_slots);
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if (likely(use_swap_slot_cache && cache->slots_ret)) {
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spin_lock_irq(&cache->free_lock);
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/* Swap slots cache may be deactivated before acquiring lock */
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if (!use_swap_slot_cache || !cache->slots_ret) {
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spin_unlock_irq(&cache->free_lock);
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goto direct_free;
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}
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if (cache->n_ret >= SWAP_SLOTS_CACHE_SIZE) {
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/*
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* Return slots to global pool.
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* The current swap_map value is SWAP_HAS_CACHE.
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* Set it to 0 to indicate it is available for
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* allocation in global pool
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*/
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swapcache_free_entries(cache->slots_ret, cache->n_ret);
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cache->n_ret = 0;
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}
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cache->slots_ret[cache->n_ret++] = entry;
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spin_unlock_irq(&cache->free_lock);
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} else {
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direct_free:
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swapcache_free_entries(&entry, 1);
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}
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return 0;
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}
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swp_entry_t get_swap_page(struct page *page)
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{
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swp_entry_t entry, *pentry;
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struct swap_slots_cache *cache;
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entry.val = 0;
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if (PageTransHuge(page)) {
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if (IS_ENABLED(CONFIG_THP_SWAP))
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get_swap_pages(1, true, &entry);
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goto out;
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}
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/*
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* Preemption is allowed here, because we may sleep
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* in refill_swap_slots_cache(). But it is safe, because
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* accesses to the per-CPU data structure are protected by the
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* mutex cache->alloc_lock.
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*
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* The alloc path here does not touch cache->slots_ret
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* so cache->free_lock is not taken.
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*/
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cache = raw_cpu_ptr(&swp_slots);
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if (likely(check_cache_active() && cache->slots)) {
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mutex_lock(&cache->alloc_lock);
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if (cache->slots) {
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repeat:
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if (cache->nr) {
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pentry = &cache->slots[cache->cur++];
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entry = *pentry;
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pentry->val = 0;
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cache->nr--;
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} else {
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if (refill_swap_slots_cache(cache))
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goto repeat;
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}
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}
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mutex_unlock(&cache->alloc_lock);
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if (entry.val)
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goto out;
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}
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get_swap_pages(1, false, &entry);
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out:
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if (mem_cgroup_try_charge_swap(page, entry)) {
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put_swap_page(page, entry);
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entry.val = 0;
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}
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return entry;
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}
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