mirror of
https://github.com/brain-hackers/linux-brain.git
synced 2024-06-09 23:36:23 +09:00
7a9cdebdcc
Jann Horn points out that the vmacache_flush_all() function is not only potentially expensive, it's buggy too. It also happens to be entirely unnecessary, because the sequence number overflow case can be avoided by simply making the sequence number be 64-bit. That doesn't even grow the data structures in question, because the other adjacent fields are already 64-bit. So simplify the whole thing by just making the sequence number overflow case go away entirely, which gets rid of all the complications and makes the code faster too. Win-win. [ Oleg Nesterov points out that the VMACACHE_FULL_FLUSHES statistics also just goes away entirely with this ] Reported-by: Jann Horn <jannh@google.com> Suggested-by: Will Deacon <will.deacon@arm.com> Acked-by: Davidlohr Bueso <dave@stgolabs.net> Cc: Oleg Nesterov <oleg@redhat.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
96 lines
2.4 KiB
C
96 lines
2.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef _LINUX_MM_TYPES_TASK_H
|
|
#define _LINUX_MM_TYPES_TASK_H
|
|
|
|
/*
|
|
* Here are the definitions of the MM data types that are embedded in 'struct task_struct'.
|
|
*
|
|
* (These are defined separately to decouple sched.h from mm_types.h as much as possible.)
|
|
*/
|
|
|
|
#include <linux/types.h>
|
|
#include <linux/threads.h>
|
|
#include <linux/atomic.h>
|
|
#include <linux/cpumask.h>
|
|
|
|
#include <asm/page.h>
|
|
|
|
#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
|
|
#include <asm/tlbbatch.h>
|
|
#endif
|
|
|
|
#define USE_SPLIT_PTE_PTLOCKS (NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS)
|
|
#define USE_SPLIT_PMD_PTLOCKS (USE_SPLIT_PTE_PTLOCKS && \
|
|
IS_ENABLED(CONFIG_ARCH_ENABLE_SPLIT_PMD_PTLOCK))
|
|
#define ALLOC_SPLIT_PTLOCKS (SPINLOCK_SIZE > BITS_PER_LONG/8)
|
|
|
|
/*
|
|
* The per task VMA cache array:
|
|
*/
|
|
#define VMACACHE_BITS 2
|
|
#define VMACACHE_SIZE (1U << VMACACHE_BITS)
|
|
#define VMACACHE_MASK (VMACACHE_SIZE - 1)
|
|
|
|
struct vmacache {
|
|
u64 seqnum;
|
|
struct vm_area_struct *vmas[VMACACHE_SIZE];
|
|
};
|
|
|
|
enum {
|
|
MM_FILEPAGES, /* Resident file mapping pages */
|
|
MM_ANONPAGES, /* Resident anonymous pages */
|
|
MM_SWAPENTS, /* Anonymous swap entries */
|
|
MM_SHMEMPAGES, /* Resident shared memory pages */
|
|
NR_MM_COUNTERS
|
|
};
|
|
|
|
#if USE_SPLIT_PTE_PTLOCKS && defined(CONFIG_MMU)
|
|
#define SPLIT_RSS_COUNTING
|
|
/* per-thread cached information, */
|
|
struct task_rss_stat {
|
|
int events; /* for synchronization threshold */
|
|
int count[NR_MM_COUNTERS];
|
|
};
|
|
#endif /* USE_SPLIT_PTE_PTLOCKS */
|
|
|
|
struct mm_rss_stat {
|
|
atomic_long_t count[NR_MM_COUNTERS];
|
|
};
|
|
|
|
struct page_frag {
|
|
struct page *page;
|
|
#if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
|
|
__u32 offset;
|
|
__u32 size;
|
|
#else
|
|
__u16 offset;
|
|
__u16 size;
|
|
#endif
|
|
};
|
|
|
|
/* Track pages that require TLB flushes */
|
|
struct tlbflush_unmap_batch {
|
|
#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
|
|
/*
|
|
* The arch code makes the following promise: generic code can modify a
|
|
* PTE, then call arch_tlbbatch_add_mm() (which internally provides all
|
|
* needed barriers), then call arch_tlbbatch_flush(), and the entries
|
|
* will be flushed on all CPUs by the time that arch_tlbbatch_flush()
|
|
* returns.
|
|
*/
|
|
struct arch_tlbflush_unmap_batch arch;
|
|
|
|
/* True if a flush is needed. */
|
|
bool flush_required;
|
|
|
|
/*
|
|
* If true then the PTE was dirty when unmapped. The entry must be
|
|
* flushed before IO is initiated or a stale TLB entry potentially
|
|
* allows an update without redirtying the page.
|
|
*/
|
|
bool writable;
|
|
#endif
|
|
};
|
|
|
|
#endif /* _LINUX_MM_TYPES_TASK_H */
|