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| author | Wolfram Sang <wsa@the-dreams.de> | 2018-05-17 16:29:19 +0200 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2018-05-17 16:29:19 +0200 |
| commit | 3d8b7a4ea310f3621a19d50cbe6cbc89bb23b82f (patch) | |
| tree | 51a261418928d8499ecade36f74e74fc92396503 /mm/mmap.c | |
| parent | c599eb4ff6e0f9c525695faab7149d8d48743b1c (diff) | |
| parent | caaccda136ae3fa1c5f6563aae22ca3c199f563a (diff) | |
| download | net-3d8b7a4ea310f3621a19d50cbe6cbc89bb23b82f.tar.gz | |
Merge branch 'i2c/platform_data-immutable' into i2c/for-4.18
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 76 |
1 files changed, 58 insertions, 18 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index 9d5968d1e8e336..78e14facdb6ed2 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1324,6 +1324,35 @@ static inline int mlock_future_check(struct mm_struct *mm, return 0; } +static inline u64 file_mmap_size_max(struct file *file, struct inode *inode) +{ + if (S_ISREG(inode->i_mode)) + return inode->i_sb->s_maxbytes; + + if (S_ISBLK(inode->i_mode)) + return MAX_LFS_FILESIZE; + + /* Special "we do even unsigned file positions" case */ + if (file->f_mode & FMODE_UNSIGNED_OFFSET) + return 0; + + /* Yes, random drivers might want more. But I'm tired of buggy drivers */ + return ULONG_MAX; +} + +static inline bool file_mmap_ok(struct file *file, struct inode *inode, + unsigned long pgoff, unsigned long len) +{ + u64 maxsize = file_mmap_size_max(file, inode); + + if (maxsize && len > maxsize) + return false; + maxsize -= len; + if (pgoff > maxsize >> PAGE_SHIFT) + return false; + return true; +} + /* * The caller must hold down_write(¤t->mm->mmap_sem). */ @@ -1409,6 +1438,9 @@ unsigned long do_mmap(struct file *file, unsigned long addr, struct inode *inode = file_inode(file); unsigned long flags_mask; + if (!file_mmap_ok(file, inode, pgoff, len)) + return -EOVERFLOW; + flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags; switch (flags & MAP_TYPE) { @@ -3024,6 +3056,32 @@ void exit_mmap(struct mm_struct *mm) /* mm's last user has gone, and its about to be pulled down */ mmu_notifier_release(mm); + if (unlikely(mm_is_oom_victim(mm))) { + /* + * Manually reap the mm to free as much memory as possible. + * Then, as the oom reaper does, set MMF_OOM_SKIP to disregard + * this mm from further consideration. Taking mm->mmap_sem for + * write after setting MMF_OOM_SKIP will guarantee that the oom + * reaper will not run on this mm again after mmap_sem is + * dropped. + * + * Nothing can be holding mm->mmap_sem here and the above call + * to mmu_notifier_release(mm) ensures mmu notifier callbacks in + * __oom_reap_task_mm() will not block. + * + * This needs to be done before calling munlock_vma_pages_all(), + * which clears VM_LOCKED, otherwise the oom reaper cannot + * reliably test it. + */ + mutex_lock(&oom_lock); + __oom_reap_task_mm(mm); + mutex_unlock(&oom_lock); + + set_bit(MMF_OOM_SKIP, &mm->flags); + down_write(&mm->mmap_sem); + up_write(&mm->mmap_sem); + } + if (mm->locked_vm) { vma = mm->mmap; while (vma) { @@ -3045,24 +3103,6 @@ void exit_mmap(struct mm_struct *mm) /* update_hiwater_rss(mm) here? but nobody should be looking */ /* Use -1 here to ensure all VMAs in the mm are unmapped */ unmap_vmas(&tlb, vma, 0, -1); - - if (unlikely(mm_is_oom_victim(mm))) { - /* - * Wait for oom_reap_task() to stop working on this - * mm. Because MMF_OOM_SKIP is already set before - * calling down_read(), oom_reap_task() will not run - * on this "mm" post up_write(). - * - * mm_is_oom_victim() cannot be set from under us - * either because victim->mm is already set to NULL - * under task_lock before calling mmput and oom_mm is - * set not NULL by the OOM killer only if victim->mm - * is found not NULL while holding the task_lock. - */ - set_bit(MMF_OOM_SKIP, &mm->flags); - down_write(&mm->mmap_sem); - up_write(&mm->mmap_sem); - } free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING); tlb_finish_mmu(&tlb, 0, -1); |