| Message ID | 20200212233946.246210-2-minchan@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | introduce memory hinting API for external process | expand |
On Wed, 2020-02-12 at 15:39 -0800, Minchan Kim wrote: > In upcoming patches, do_madvise will be called from external process > context so it shouldn't asssume "current" is always hinted process's > task_struct. Thus, let's get the mm_struct from vma->vm_mm, not > current because vma is always hinted process's one. And let's pass > *current* as new task argument of do_madvise so it shouldn't change > existing behavior. > > Signed-off-by: Minchan Kim <minchan@kernel.org> > --- > fs/io_uring.c | 2 +- > include/linux/mm.h | 3 ++- > mm/madvise.c | 37 ++++++++++++++++++++----------------- > 3 files changed, 23 insertions(+), 19 deletions(-) > > diff --git a/fs/io_uring.c b/fs/io_uring.c > index 63beda9bafc5..6307206b970f 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -2736,7 +2736,7 @@ static int io_madvise(struct io_kiocb *req, struct io_kiocb **nxt, > if (force_nonblock) > return -EAGAIN; > > - ret = do_madvise(ma->addr, ma->len, ma->advice); > + ret = do_madvise(current, ma->addr, ma->len, ma->advice); > if (ret < 0) > req_set_fail_links(req); > io_cqring_add_event(req, ret); > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 52269e56c514..8cb41131ec96 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -2323,7 +2323,8 @@ extern int __do_munmap(struct mm_struct *, unsigned long, size_t, > struct list_head *uf, bool downgrade); > extern int do_munmap(struct mm_struct *, unsigned long, size_t, > struct list_head *uf); > -extern int do_madvise(unsigned long start, size_t len_in, int behavior); > +extern int do_madvise(struct task_struct *task, unsigned long start, > + size_t len_in, int behavior); > > static inline unsigned long > do_mmap_pgoff(struct file *file, unsigned long addr, > diff --git a/mm/madvise.c b/mm/madvise.c > index 43b47d3fae02..ab4011ba2d9e 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -256,6 +256,7 @@ static long madvise_willneed(struct vm_area_struct *vma, > { > struct file *file = vma->vm_file; > loff_t offset; > + struct mm_struct *mm = vma->vm_mm; > > *prev = vma; > #ifdef CONFIG_SWAP I would probably move the declaration of the mm variable to the top just so you don't have the large "offset" valley between the two long variable declarations. > @@ -288,12 +289,12 @@ static long madvise_willneed(struct vm_area_struct *vma, > */ > *prev = NULL; /* tell sys_madvise we drop mmap_sem */ > get_file(file); > - up_read(¤t->mm->mmap_sem); > + up_read(&mm->mmap_sem); > offset = (loff_t)(start - vma->vm_start) > + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); > vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED); > fput(file); > - down_read(¤t->mm->mmap_sem); > + down_read(&mm->mmap_sem); > return 0; > } > > @@ -674,9 +675,7 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, > } > out: > if (nr_swap) { > - if (current->mm == mm) > - sync_mm_rss(mm); > - > + sync_mm_rss(mm); > add_mm_counter(mm, MM_SWAPENTS, nr_swap); > } > arch_leave_lazy_mmu_mode(); This seems like it is taking things in the opposite direction of the other changes. sync_mm_rss will operate on current if I am not mistaken. I don't think you would want to add the stats from current to the stats of the task you are updating. It might make sense to add a new function that would allow you to sync the remote task stats by creaing a version of sync_mm_rss that also takes a task pointer. > @@ -756,6 +755,7 @@ static long madvise_dontneed_free(struct vm_area_struct *vma, > unsigned long start, unsigned long end, > int behavior) > { > + struct mm_struct *mm = vma->vm_mm; > *prev = vma; > if (!can_madv_lru_vma(vma)) > return -EINVAL; > @@ -763,8 +763,8 @@ static long madvise_dontneed_free(struct vm_area_struct *vma, > if (!userfaultfd_remove(vma, start, end)) { > *prev = NULL; /* mmap_sem has been dropped, prev is stale */ > > - down_read(¤t->mm->mmap_sem); > - vma = find_vma(current->mm, start); > + down_read(&mm->mmap_sem); > + vma = find_vma(mm, start); > if (!vma) > return -ENOMEM; > if (start < vma->vm_start) { This piece of code has me wondering if it is valid to be using vma->mm at the start of the function. I assume we are probably safe since we read the mm value before the semaphore was released in userfaultfd_remove. It might make more sense to just pass the task to the function and use task->mm- >mmap_sem instead. It might be simpler, safer, and easier to review to just go through and add the task struct as needed and then simply replace references to current->mm with task->mm. > @@ -818,6 +818,7 @@ static long madvise_remove(struct vm_area_struct *vma, > loff_t offset; > int error; > struct file *f; > + struct mm_struct *mm = vma->vm_mm; > > *prev = NULL; /* tell sys_madvise we drop mmap_sem */ > > @@ -845,13 +846,13 @@ static long madvise_remove(struct vm_area_struct *vma, > get_file(f); > if (userfaultfd_remove(vma, start, end)) { > /* mmap_sem was not released by userfaultfd_remove() */ > - up_read(¤t->mm->mmap_sem); > + up_read(&mm->mmap_sem); > } > error = vfs_fallocate(f, > FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, > offset, end - start); > fput(f); > - down_read(¤t->mm->mmap_sem); > + down_read(&mm->mmap_sem); > return error; > } > > @@ -1044,7 +1045,8 @@ madvise_behavior_valid(int behavior) > * -EBADF - map exists, but area maps something that isn't a file. > * -EAGAIN - a kernel resource was temporarily unavailable. > */ > -int do_madvise(unsigned long start, size_t len_in, int behavior) > +int do_madvise(struct task_struct *task, unsigned long start, > + size_t len_in, int behavior) > { > unsigned long end, tmp; > struct vm_area_struct *vma, *prev; > @@ -1053,6 +1055,7 @@ int do_madvise(unsigned long start, size_t len_in, int behavior) > int write; > size_t len; > struct blk_plug plug; > + struct mm_struct *mm = task->mm; > > start = untagged_addr(start); > > @@ -1082,10 +1085,10 @@ int do_madvise(unsigned long start, size_t len_in, int behavior) > > write = madvise_need_mmap_write(behavior); > if (write) { > - if (down_write_killable(¤t->mm->mmap_sem)) > + if (down_write_killable(&mm->mmap_sem)) > return -EINTR; > } else { > - down_read(¤t->mm->mmap_sem); > + down_read(&mm->mmap_sem); > } > > /* > @@ -1093,7 +1096,7 @@ int do_madvise(unsigned long start, size_t len_in, int behavior) > * ranges, just ignore them, but return -ENOMEM at the end. > * - different from the way of handling in mlock etc. > */ > - vma = find_vma_prev(current->mm, start, &prev); > + vma = find_vma_prev(mm, start, &prev); > if (vma && start > vma->vm_start) > prev = vma; > > @@ -1130,19 +1133,19 @@ int do_madvise(unsigned long start, size_t len_in, int behavior) > if (prev) > vma = prev->vm_next; > else /* madvise_remove dropped mmap_sem */ > - vma = find_vma(current->mm, start); > + vma = find_vma(mm, start); > } > out: > blk_finish_plug(&plug); > if (write) > - up_write(¤t->mm->mmap_sem); > + up_write(&mm->mmap_sem); > else > - up_read(¤t->mm->mmap_sem); > + up_read(&mm->mmap_sem); > > return error; > } > > SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior) > { > - return do_madvise(start, len_in, behavior); > + return do_madvise(current, start, len_in, behavior); > }
On Wed, Feb 12, 2020 at 04:21:59PM -0800, Alexander Duyck wrote: > On Wed, 2020-02-12 at 15:39 -0800, Minchan Kim wrote: > > In upcoming patches, do_madvise will be called from external process > > context so it shouldn't asssume "current" is always hinted process's > > task_struct. Thus, let's get the mm_struct from vma->vm_mm, not > > current because vma is always hinted process's one. And let's pass > > *current* as new task argument of do_madvise so it shouldn't change > > existing behavior. > > > > Signed-off-by: Minchan Kim <minchan@kernel.org> > > --- > > fs/io_uring.c | 2 +- > > include/linux/mm.h | 3 ++- > > mm/madvise.c | 37 ++++++++++++++++++++----------------- > > 3 files changed, 23 insertions(+), 19 deletions(-) > > > > diff --git a/fs/io_uring.c b/fs/io_uring.c > > index 63beda9bafc5..6307206b970f 100644 > > --- a/fs/io_uring.c > > +++ b/fs/io_uring.c > > @@ -2736,7 +2736,7 @@ static int io_madvise(struct io_kiocb *req, struct io_kiocb **nxt, > > if (force_nonblock) > > return -EAGAIN; > > > > - ret = do_madvise(ma->addr, ma->len, ma->advice); > > + ret = do_madvise(current, ma->addr, ma->len, ma->advice); > > if (ret < 0) > > req_set_fail_links(req); > > io_cqring_add_event(req, ret); > > diff --git a/include/linux/mm.h b/include/linux/mm.h > > index 52269e56c514..8cb41131ec96 100644 > > --- a/include/linux/mm.h > > +++ b/include/linux/mm.h > > @@ -2323,7 +2323,8 @@ extern int __do_munmap(struct mm_struct *, unsigned long, size_t, > > struct list_head *uf, bool downgrade); > > extern int do_munmap(struct mm_struct *, unsigned long, size_t, > > struct list_head *uf); > > -extern int do_madvise(unsigned long start, size_t len_in, int behavior); > > +extern int do_madvise(struct task_struct *task, unsigned long start, > > + size_t len_in, int behavior); > > > > static inline unsigned long > > do_mmap_pgoff(struct file *file, unsigned long addr, > > diff --git a/mm/madvise.c b/mm/madvise.c > > index 43b47d3fae02..ab4011ba2d9e 100644 > > --- a/mm/madvise.c > > +++ b/mm/madvise.c > > @@ -256,6 +256,7 @@ static long madvise_willneed(struct vm_area_struct *vma, > > { > > struct file *file = vma->vm_file; > > loff_t offset; > > + struct mm_struct *mm = vma->vm_mm; > > > > *prev = vma; > > #ifdef CONFIG_SWAP > > I would probably move the declaration of the mm variable to the top just > so you don't have the large "offset" valley between the two long variable > declarations. No problem. > > > @@ -288,12 +289,12 @@ static long madvise_willneed(struct vm_area_struct *vma, > > */ > > *prev = NULL; /* tell sys_madvise we drop mmap_sem */ > > get_file(file); > > - up_read(¤t->mm->mmap_sem); > > + up_read(&mm->mmap_sem); > > offset = (loff_t)(start - vma->vm_start) > > + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); > > vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED); > > fput(file); > > - down_read(¤t->mm->mmap_sem); > > + down_read(&mm->mmap_sem); > > return 0; > > } > > > > @@ -674,9 +675,7 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, > > } > > out: > > if (nr_swap) { > > - if (current->mm == mm) > > - sync_mm_rss(mm); > > - > > + sync_mm_rss(mm); > > add_mm_counter(mm, MM_SWAPENTS, nr_swap); > > } > > arch_leave_lazy_mmu_mode(); > > This seems like it is taking things in the opposite direction of the other > changes. sync_mm_rss will operate on current if I am not mistaken. I don't > think you would want to add the stats from current to the stats of the > task you are updating. > > It might make sense to add a new function that would allow you to sync the > remote task stats by creaing a version of sync_mm_rss that also takes a > task pointer. Sorry, that part was intended for other patch regardless of this patchset but squeezed into this version by my mistake. I wanted to remove those part from madvise_free because currently madvise_free is always done in current context. I will drop it in next revision since it's not related to this patchset. > > > @@ -756,6 +755,7 @@ static long madvise_dontneed_free(struct vm_area_struct *vma, > > unsigned long start, unsigned long end, > > int behavior) > > { > > + struct mm_struct *mm = vma->vm_mm; > > *prev = vma; > > if (!can_madv_lru_vma(vma)) > > return -EINVAL; > > @@ -763,8 +763,8 @@ static long madvise_dontneed_free(struct vm_area_struct *vma, > > if (!userfaultfd_remove(vma, start, end)) { > > *prev = NULL; /* mmap_sem has been dropped, prev is stale */ > > > > - down_read(¤t->mm->mmap_sem); > > - vma = find_vma(current->mm, start); > > + down_read(&mm->mmap_sem); > > + vma = find_vma(mm, start); > > if (!vma) > > return -ENOMEM; > > if (start < vma->vm_start) { > > This piece of code has me wondering if it is valid to be using vma->mm at > the start of the function. I assume we are probably safe since we read the > mm value before the semaphore was released in userfaultfd_remove. It might > make more sense to just pass the task to the function and use task->mm- > >mmap_sem instead. As Jann pointed out, we couldn't use task->mm once we verified it via access_mm. However, I believe vma->vm_mm is safe(Ccing Jann for double check). > > It might be simpler, safer, and easier to review to just go through and > add the task struct as needed and then simply replace references to > current->mm with task->mm. > > > @@ -818,6 +818,7 @@ static long madvise_remove(struct vm_area_struct *vma, > > loff_t offset; > > int error; > > struct file *f; > > + struct mm_struct *mm = vma->vm_mm; > > > > *prev = NULL; /* tell sys_madvise we drop mmap_sem */ > > > > @@ -845,13 +846,13 @@ static long madvise_remove(struct vm_area_struct *vma, > > get_file(f); > > if (userfaultfd_remove(vma, start, end)) { > > /* mmap_sem was not released by userfaultfd_remove() */ > > - up_read(¤t->mm->mmap_sem); > > + up_read(&mm->mmap_sem); > > } > > error = vfs_fallocate(f, > > FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, > > offset, end - start); > > fput(f); > > - down_read(¤t->mm->mmap_sem); > > + down_read(&mm->mmap_sem); > > return error; > > } > > > > @@ -1044,7 +1045,8 @@ madvise_behavior_valid(int behavior) > > * -EBADF - map exists, but area maps something that isn't a file. > > * -EAGAIN - a kernel resource was temporarily unavailable. > > */ > > -int do_madvise(unsigned long start, size_t len_in, int behavior) > > +int do_madvise(struct task_struct *task, unsigned long start, > > + size_t len_in, int behavior) > > { > > unsigned long end, tmp; > > struct vm_area_struct *vma, *prev; > > @@ -1053,6 +1055,7 @@ int do_madvise(unsigned long start, size_t len_in, int behavior) > > int write; > > size_t len; > > struct blk_plug plug; > > + struct mm_struct *mm = task->mm; > > > > start = untagged_addr(start); > > > > @@ -1082,10 +1085,10 @@ int do_madvise(unsigned long start, size_t len_in, int behavior) > > > > write = madvise_need_mmap_write(behavior); > > if (write) { > > - if (down_write_killable(¤t->mm->mmap_sem)) > > + if (down_write_killable(&mm->mmap_sem)) > > return -EINTR; > > } else { > > - down_read(¤t->mm->mmap_sem); > > + down_read(&mm->mmap_sem); > > } > > > > /* > > @@ -1093,7 +1096,7 @@ int do_madvise(unsigned long start, size_t len_in, int behavior) > > * ranges, just ignore them, but return -ENOMEM at the end. > > * - different from the way of handling in mlock etc. > > */ > > - vma = find_vma_prev(current->mm, start, &prev); > > + vma = find_vma_prev(mm, start, &prev); > > if (vma && start > vma->vm_start) > > prev = vma; > > > > @@ -1130,19 +1133,19 @@ int do_madvise(unsigned long start, size_t len_in, int behavior) > > if (prev) > > vma = prev->vm_next; > > else /* madvise_remove dropped mmap_sem */ > > - vma = find_vma(current->mm, start); > > + vma = find_vma(mm, start); > > } > > out: > > blk_finish_plug(&plug); > > if (write) > > - up_write(¤t->mm->mmap_sem); > > + up_write(&mm->mmap_sem); > > else > > - up_read(¤t->mm->mmap_sem); > > + up_read(&mm->mmap_sem); > > > > return error; > > } > > > > SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior) > > { > > - return do_madvise(start, len_in, behavior); > > + return do_madvise(current, start, len_in, behavior); > > } > >
On Thu, Feb 13, 2020 at 6:02 PM Minchan Kim <minchan@kernel.org> wrote: > On Wed, Feb 12, 2020 at 04:21:59PM -0800, Alexander Duyck wrote: > > On Wed, 2020-02-12 at 15:39 -0800, Minchan Kim wrote: > > > In upcoming patches, do_madvise will be called from external process > > > context so it shouldn't asssume "current" is always hinted process's > > > task_struct. Thus, let's get the mm_struct from vma->vm_mm, not > > > current because vma is always hinted process's one. And let's pass > > > *current* as new task argument of do_madvise so it shouldn't change > > > existing behavior. [...] > > > @@ -763,8 +763,8 @@ static long madvise_dontneed_free(struct vm_area_struct *vma, > > > if (!userfaultfd_remove(vma, start, end)) { > > > *prev = NULL; /* mmap_sem has been dropped, prev is stale */ > > > > > > - down_read(¤t->mm->mmap_sem); > > > - vma = find_vma(current->mm, start); > > > + down_read(&mm->mmap_sem); > > > + vma = find_vma(mm, start); > > > if (!vma) > > > return -ENOMEM; > > > if (start < vma->vm_start) { > > > > This piece of code has me wondering if it is valid to be using vma->mm at > > the start of the function. I assume we are probably safe since we read the > > mm value before the semaphore was released in userfaultfd_remove. It might > > make more sense to just pass the task to the function and use task->mm- > > >mmap_sem instead. > > As Jann pointed out, we couldn't use task->mm once we verified it via > access_mm. However, I believe vma->vm_mm is safe(Ccing Jann for double > check). Looks safe to me, too.
diff --git a/fs/io_uring.c b/fs/io_uring.c index 63beda9bafc5..6307206b970f 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -2736,7 +2736,7 @@ static int io_madvise(struct io_kiocb *req, struct io_kiocb **nxt, if (force_nonblock) return -EAGAIN; - ret = do_madvise(ma->addr, ma->len, ma->advice); + ret = do_madvise(current, ma->addr, ma->len, ma->advice); if (ret < 0) req_set_fail_links(req); io_cqring_add_event(req, ret); diff --git a/include/linux/mm.h b/include/linux/mm.h index 52269e56c514..8cb41131ec96 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2323,7 +2323,8 @@ extern int __do_munmap(struct mm_struct *, unsigned long, size_t, struct list_head *uf, bool downgrade); extern int do_munmap(struct mm_struct *, unsigned long, size_t, struct list_head *uf); -extern int do_madvise(unsigned long start, size_t len_in, int behavior); +extern int do_madvise(struct task_struct *task, unsigned long start, + size_t len_in, int behavior); static inline unsigned long do_mmap_pgoff(struct file *file, unsigned long addr, diff --git a/mm/madvise.c b/mm/madvise.c index 43b47d3fae02..ab4011ba2d9e 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -256,6 +256,7 @@ static long madvise_willneed(struct vm_area_struct *vma, { struct file *file = vma->vm_file; loff_t offset; + struct mm_struct *mm = vma->vm_mm; *prev = vma; #ifdef CONFIG_SWAP @@ -288,12 +289,12 @@ static long madvise_willneed(struct vm_area_struct *vma, */ *prev = NULL; /* tell sys_madvise we drop mmap_sem */ get_file(file); - up_read(¤t->mm->mmap_sem); + up_read(&mm->mmap_sem); offset = (loff_t)(start - vma->vm_start) + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED); fput(file); - down_read(¤t->mm->mmap_sem); + down_read(&mm->mmap_sem); return 0; } @@ -674,9 +675,7 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, } out: if (nr_swap) { - if (current->mm == mm) - sync_mm_rss(mm); - + sync_mm_rss(mm); add_mm_counter(mm, MM_SWAPENTS, nr_swap); } arch_leave_lazy_mmu_mode(); @@ -756,6 +755,7 @@ static long madvise_dontneed_free(struct vm_area_struct *vma, unsigned long start, unsigned long end, int behavior) { + struct mm_struct *mm = vma->vm_mm; *prev = vma; if (!can_madv_lru_vma(vma)) return -EINVAL; @@ -763,8 +763,8 @@ static long madvise_dontneed_free(struct vm_area_struct *vma, if (!userfaultfd_remove(vma, start, end)) { *prev = NULL; /* mmap_sem has been dropped, prev is stale */ - down_read(¤t->mm->mmap_sem); - vma = find_vma(current->mm, start); + down_read(&mm->mmap_sem); + vma = find_vma(mm, start); if (!vma) return -ENOMEM; if (start < vma->vm_start) { @@ -818,6 +818,7 @@ static long madvise_remove(struct vm_area_struct *vma, loff_t offset; int error; struct file *f; + struct mm_struct *mm = vma->vm_mm; *prev = NULL; /* tell sys_madvise we drop mmap_sem */ @@ -845,13 +846,13 @@ static long madvise_remove(struct vm_area_struct *vma, get_file(f); if (userfaultfd_remove(vma, start, end)) { /* mmap_sem was not released by userfaultfd_remove() */ - up_read(¤t->mm->mmap_sem); + up_read(&mm->mmap_sem); } error = vfs_fallocate(f, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, offset, end - start); fput(f); - down_read(¤t->mm->mmap_sem); + down_read(&mm->mmap_sem); return error; } @@ -1044,7 +1045,8 @@ madvise_behavior_valid(int behavior) * -EBADF - map exists, but area maps something that isn't a file. * -EAGAIN - a kernel resource was temporarily unavailable. */ -int do_madvise(unsigned long start, size_t len_in, int behavior) +int do_madvise(struct task_struct *task, unsigned long start, + size_t len_in, int behavior) { unsigned long end, tmp; struct vm_area_struct *vma, *prev; @@ -1053,6 +1055,7 @@ int do_madvise(unsigned long start, size_t len_in, int behavior) int write; size_t len; struct blk_plug plug; + struct mm_struct *mm = task->mm; start = untagged_addr(start); @@ -1082,10 +1085,10 @@ int do_madvise(unsigned long start, size_t len_in, int behavior) write = madvise_need_mmap_write(behavior); if (write) { - if (down_write_killable(¤t->mm->mmap_sem)) + if (down_write_killable(&mm->mmap_sem)) return -EINTR; } else { - down_read(¤t->mm->mmap_sem); + down_read(&mm->mmap_sem); } /* @@ -1093,7 +1096,7 @@ int do_madvise(unsigned long start, size_t len_in, int behavior) * ranges, just ignore them, but return -ENOMEM at the end. * - different from the way of handling in mlock etc. */ - vma = find_vma_prev(current->mm, start, &prev); + vma = find_vma_prev(mm, start, &prev); if (vma && start > vma->vm_start) prev = vma; @@ -1130,19 +1133,19 @@ int do_madvise(unsigned long start, size_t len_in, int behavior) if (prev) vma = prev->vm_next; else /* madvise_remove dropped mmap_sem */ - vma = find_vma(current->mm, start); + vma = find_vma(mm, start); } out: blk_finish_plug(&plug); if (write) - up_write(¤t->mm->mmap_sem); + up_write(&mm->mmap_sem); else - up_read(¤t->mm->mmap_sem); + up_read(&mm->mmap_sem); return error; } SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior) { - return do_madvise(start, len_in, behavior); + return do_madvise(current, start, len_in, behavior); }
In upcoming patches, do_madvise will be called from external process context so it shouldn't asssume "current" is always hinted process's task_struct. Thus, let's get the mm_struct from vma->vm_mm, not current because vma is always hinted process's one. And let's pass *current* as new task argument of do_madvise so it shouldn't change existing behavior. Signed-off-by: Minchan Kim <minchan@kernel.org> --- fs/io_uring.c | 2 +- include/linux/mm.h | 3 ++- mm/madvise.c | 37 ++++++++++++++++++++----------------- 3 files changed, 23 insertions(+), 19 deletions(-)