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mm/munlock: protect the per-CPU pagevec by a local_lock_t

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The access to mlock_pvec is protected by disabling preemption via
get_cpu_var() or implicit by having preemption disabled by the caller
(in mlock_page_drain() case).  This breaks on PREEMPT_RT since
folio_lruvec_lock_irq() acquires a sleeping lock in this section.

Create struct mlock_pvec which consits of the local_lock_t and the
pagevec.  Acquire the local_lock() before accessing the per-CPU pagevec.
Replace mlock_page_drain() with a _local() version which is invoked on
the local CPU and acquires the local_lock_t and a _remote() version
which uses the pagevec from a remote CPU which offline.

Link: https://lkml.kernel.org/r/YjizWi9IY0mpvIfb@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Sebastian Andrzej Siewior 2022-04-01 11:28:33 -07:00 committed by Linus Torvalds
parent 577e9846f8
commit adb11e78c5
6 changed files with 47 additions and 16 deletions
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6
mm/internal.h
View file

@ -456,7 +456,8 @@ static inline void munlock_vma_page(struct page *page,
}
void mlock_new_page(struct page *page);
bool need_mlock_page_drain(int cpu);
void mlock_page_drain(int cpu);
void mlock_page_drain_local(void);
void mlock_page_drain_remote(int cpu);
extern pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma);
@ -539,7 +540,8 @@ static inline void munlock_vma_page(struct page *page,
struct vm_area_struct *vma, bool compound) { }
static inline void mlock_new_page(struct page *page) { }
static inline bool need_mlock_page_drain(int cpu) { return false; }
static inline void mlock_page_drain(int cpu) { }
static inline void mlock_page_drain_local(void) { }
static inline void mlock_page_drain_remote(int cpu) { }
static inline void vunmap_range_noflush(unsigned long start, unsigned long end)
{
}

2
mm/migrate.c
View file

@ -246,7 +246,7 @@ static bool remove_migration_pte(struct folio *folio,
set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
}
if (vma->vm_flags & VM_LOCKED)
mlock_page_drain(smp_processor_id());
mlock_page_drain_local();
trace_remove_migration_pte(pvmw.address, pte_val(pte),
compound_order(new));

46
mm/mlock.c
View file

@ -28,7 +28,14 @@
#include "internal.h"
static DEFINE_PER_CPU(struct pagevec, mlock_pvec);
struct mlock_pvec {
local_lock_t lock;
struct pagevec vec;
};
static DEFINE_PER_CPU(struct mlock_pvec, mlock_pvec) = {
.lock = INIT_LOCAL_LOCK(lock),
};
bool can_do_mlock(void)
{
@ -203,18 +210,30 @@ static void mlock_pagevec(struct pagevec *pvec)
pagevec_reinit(pvec);
}
void mlock_page_drain(int cpu)
void mlock_page_drain_local(void)
{
struct pagevec *pvec;
pvec = &per_cpu(mlock_pvec, cpu);
local_lock(&mlock_pvec.lock);
pvec = this_cpu_ptr(&mlock_pvec.vec);
if (pagevec_count(pvec))
mlock_pagevec(pvec);
local_unlock(&mlock_pvec.lock);
}
void mlock_page_drain_remote(int cpu)
{
struct pagevec *pvec;
WARN_ON_ONCE(cpu_online(cpu));
pvec = &per_cpu(mlock_pvec.vec, cpu);
if (pagevec_count(pvec))
mlock_pagevec(pvec);
}
bool need_mlock_page_drain(int cpu)
{
return pagevec_count(&per_cpu(mlock_pvec, cpu));
return pagevec_count(&per_cpu(mlock_pvec.vec, cpu));
}
/**
@ -223,7 +242,10 @@ bool need_mlock_page_drain(int cpu)
*/
void mlock_folio(struct folio *folio)
{
struct pagevec *pvec = &get_cpu_var(mlock_pvec);
struct pagevec *pvec;
local_lock(&mlock_pvec.lock);
pvec = this_cpu_ptr(&mlock_pvec.vec);
if (!folio_test_set_mlocked(folio)) {
int nr_pages = folio_nr_pages(folio);
@ -236,7 +258,7 @@ void mlock_folio(struct folio *folio)
if (!pagevec_add(pvec, mlock_lru(&folio->page)) ||
folio_test_large(folio) || lru_cache_disabled())
mlock_pagevec(pvec);
put_cpu_var(mlock_pvec);
local_unlock(&mlock_pvec.lock);
}
/**
@ -245,9 +267,11 @@ void mlock_folio(struct folio *folio)
*/
void mlock_new_page(struct page *page)
{
struct pagevec *pvec = &get_cpu_var(mlock_pvec);
struct pagevec *pvec;
int nr_pages = thp_nr_pages(page);
local_lock(&mlock_pvec.lock);
pvec = this_cpu_ptr(&mlock_pvec.vec);
SetPageMlocked(page);
mod_zone_page_state(page_zone(page), NR_MLOCK, nr_pages);
__count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages);
@ -256,7 +280,7 @@ void mlock_new_page(struct page *page)
if (!pagevec_add(pvec, mlock_new(page)) ||
PageHead(page) || lru_cache_disabled())
mlock_pagevec(pvec);
put_cpu_var(mlock_pvec);
local_unlock(&mlock_pvec.lock);
}
/**
@ -265,8 +289,10 @@ void mlock_new_page(struct page *page)
*/
void munlock_page(struct page *page)
{
struct pagevec *pvec = &get_cpu_var(mlock_pvec);
struct pagevec *pvec;
local_lock(&mlock_pvec.lock);
pvec = this_cpu_ptr(&mlock_pvec.vec);
/*
* TestClearPageMlocked(page) must be left to __munlock_page(),
* which will check whether the page is multiply mlocked.
@ -276,7 +302,7 @@ void munlock_page(struct page *page)
if (!pagevec_add(pvec, page) ||
PageHead(page) || lru_cache_disabled())
mlock_pagevec(pvec);
put_cpu_var(mlock_pvec);
local_unlock(&mlock_pvec.lock);
}
static int mlock_pte_range(pmd_t *pmd, unsigned long addr,

1
mm/page_alloc.c
View file

@ -8367,6 +8367,7 @@ static int page_alloc_cpu_dead(unsigned int cpu)
struct zone *zone;
lru_add_drain_cpu(cpu);
mlock_page_drain_remote(cpu);
drain_pages(cpu);
/*

4
mm/rmap.c
View file

@ -1683,7 +1683,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
*/
page_remove_rmap(subpage, vma, folio_test_hugetlb(folio));
if (vma->vm_flags & VM_LOCKED)
mlock_page_drain(smp_processor_id());
mlock_page_drain_local();
folio_put(folio);
}
@ -1961,7 +1961,7 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
*/
page_remove_rmap(subpage, vma, folio_test_hugetlb(folio));
if (vma->vm_flags & VM_LOCKED)
mlock_page_drain(smp_processor_id());
mlock_page_drain_local();
folio_put(folio);
}

4
mm/swap.c
View file

@ -624,7 +624,6 @@ void lru_add_drain_cpu(int cpu)
pagevec_lru_move_fn(pvec, lru_lazyfree_fn);
activate_page_drain(cpu);
mlock_page_drain(cpu);
}
/**
@ -706,6 +705,7 @@ void lru_add_drain(void)
local_lock(&lru_pvecs.lock);
lru_add_drain_cpu(smp_processor_id());
local_unlock(&lru_pvecs.lock);
mlock_page_drain_local();
}
/*
@ -720,6 +720,7 @@ static void lru_add_and_bh_lrus_drain(void)
lru_add_drain_cpu(smp_processor_id());
local_unlock(&lru_pvecs.lock);
invalidate_bh_lrus_cpu();
mlock_page_drain_local();
}
void lru_add_drain_cpu_zone(struct zone *zone)
@ -728,6 +729,7 @@ void lru_add_drain_cpu_zone(struct zone *zone)
lru_add_drain_cpu(smp_processor_id());
drain_local_pages(zone);
local_unlock(&lru_pvecs.lock);
mlock_page_drain_local();
}
#ifdef CONFIG_SMP