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| author | Lorenzo Stoakes (Oracle) <ljs@kernel.org> | 2026-03-11 20:24:37 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-04-05 23:53:28 +0300 |
| commit | 2d1e54aab6fd01f7502af20e125312e06a15bf9c (patch) | |
| tree | ed7675c9ded1fe21974dcf65f93b27598435809b /tools | |
| parent | 9b9b8d4aebf1eb8fe22293dcfc38c600a7e7859b (diff) | |
| download | linux-2d1e54aab6fd01f7502af20e125312e06a15bf9c.tar.xz | |
mm: abstract reading sysctl_max_map_count, and READ_ONCE()
Concurrent reads and writes of sysctl_max_map_count are possible, so we
should READ_ONCE() and WRITE_ONCE().
The sysctl procfs logic already enforces WRITE_ONCE(), so abstract the
read side with get_sysctl_max_map_count().
While we're here, also move the field to mm/internal.h and add the getter
there since only mm interacts with it, there's no need for anybody else to
have access.
Finally, update the VMA userland tests to reflect the change.
Link: https://lkml.kernel.org/r/0715259eb37cbdfde4f9e5db92a20ec7110a1ce5.1773249037.git.ljs@kernel.org
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Cc: Jann Horn <jannh@google.com>
Cc: Jianzhou Zhao <luckd0g@163.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/testing/vma/include/custom.h | 3 | ||||
| -rw-r--r-- | tools/testing/vma/include/dup.h | 9 | ||||
| -rw-r--r-- | tools/testing/vma/main.c | 2 |
3 files changed, 11 insertions, 3 deletions
diff --git a/tools/testing/vma/include/custom.h b/tools/testing/vma/include/custom.h index 7150e09122b2..6c62a38a2f6f 100644 --- a/tools/testing/vma/include/custom.h +++ b/tools/testing/vma/include/custom.h @@ -21,9 +21,6 @@ extern unsigned long dac_mmap_min_addr; #define VM_BUG_ON(_expr) (BUG_ON(_expr)) #define VM_BUG_ON_VMA(_expr, _vma) (BUG_ON(_expr)) -/* We hardcode this for now. */ -#define sysctl_max_map_count 0x1000000UL - #define TASK_SIZE ((1ul << 47)-PAGE_SIZE) /* diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/dup.h index 5eb313beb43d..8865ffe046d8 100644 --- a/tools/testing/vma/include/dup.h +++ b/tools/testing/vma/include/dup.h @@ -419,6 +419,9 @@ struct vma_iterator { #define EMPTY_VMA_FLAGS ((vma_flags_t){ }) +#define MAPCOUNT_ELF_CORE_MARGIN (5) +#define DEFAULT_MAX_MAP_COUNT (USHRT_MAX - MAPCOUNT_ELF_CORE_MARGIN) + /* What action should be taken after an .mmap_prepare call is complete? */ enum mmap_action_type { MMAP_NOTHING, /* Mapping is complete, no further action. */ @@ -1342,3 +1345,9 @@ static inline void vma_set_file(struct vm_area_struct *vma, struct file *file) swap(vma->vm_file, file); fput(file); } + +extern int sysctl_max_map_count; +static inline int get_sysctl_max_map_count(void) +{ + return READ_ONCE(sysctl_max_map_count); +} diff --git a/tools/testing/vma/main.c b/tools/testing/vma/main.c index 49b09e97a51f..18338f5d29e0 100644 --- a/tools/testing/vma/main.c +++ b/tools/testing/vma/main.c @@ -14,6 +14,8 @@ #include "tests/mmap.c" #include "tests/vma.c" +int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; + /* Helper functions which utilise static kernel functions. */ struct vm_area_struct *merge_existing(struct vma_merge_struct *vmg) |