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Revert "mm: relocate 'write_protect_seq' in struct mm_struct"

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This reverts commit 2e3025434a6ba090c85871a1d4080ff784109e1f.

It breaks the abi right now, but will come back in through the
`android12-5.10` branch in the near future.

Bug: 161946584
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I5db1a5a7d6025c34528a57544928a89b2c2570b5
This commit is contained in:
Greg Kroah-Hartman
2021-06-23 19:46:11 +02:00
parent 948d38f94d
commit 76d5608135
1 changed files with 7 additions and 20 deletions
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27
include/linux/mm_types.h
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@@ -468,6 +468,13 @@ struct mm_struct {
*/
atomic_t has_pinned;
/**
* @write_protect_seq: Locked when any thread is write
* protecting pages mapped by this mm to enforce a later COW,
* for instance during page table copying for fork().
*/
seqcount_t write_protect_seq;
#ifdef CONFIG_MMU
atomic_long_t pgtables_bytes; /* PTE page table pages */
#endif
@@ -476,18 +483,6 @@ struct mm_struct {
spinlock_t page_table_lock; /* Protects page tables and some
* counters
*/
/*
* With some kernel config, the current mmap_lock's offset
* inside 'mm_struct' is at 0x120, which is very optimal, as
* its two hot fields 'count' and 'owner' sit in 2 different
* cachelines, and when mmap_lock is highly contended, both
* of the 2 fields will be accessed frequently, current layout
* will help to reduce cache bouncing.
*
* So please be careful with adding new fields before
* mmap_lock, which can easily push the 2 fields into one
* cacheline.
*/
struct rw_semaphore mmap_lock;
struct list_head mmlist; /* List of maybe swapped mm's. These
@@ -508,15 +503,7 @@ struct mm_struct {
unsigned long stack_vm; /* VM_STACK */
unsigned long def_flags;
/**
* @write_protect_seq: Locked when any thread is write
* protecting pages mapped by this mm to enforce a later COW,
* for instance during page table copying for fork().
*/
seqcount_t write_protect_seq;
spinlock_t arg_lock; /* protect the below fields */
unsigned long start_code, end_code, start_data, end_data;
unsigned long start_brk, brk, start_stack;
unsigned long arg_start, arg_end, env_start, env_end;