| Message ID | 20211201142918.921493-50-Liam.Howlett@oracle.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Introducing the Maple Tree | expand |
On 12/1/21 15:30, Liam Howlett wrote: > From: "Liam R. Howlett" <Liam.Howlett@Oracle.com> > > Use vma_next() and remove reference to the start of the linked list > > Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com> > --- > kernel/bpf/task_iter.c | 21 ++++----------------- > 1 file changed, 4 insertions(+), 17 deletions(-) > > diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c > index b48750bfba5a..2d964743f1e6 100644 > --- a/kernel/bpf/task_iter.c > +++ b/kernel/bpf/task_iter.c > @@ -299,8 +299,8 @@ struct bpf_iter_seq_task_vma_info { > }; > > enum bpf_task_vma_iter_find_op { > - task_vma_iter_first_vma, /* use mm->mmap */ > - task_vma_iter_next_vma, /* use curr_vma->vm_next */ > + task_vma_iter_first_vma, /* use find_vma() with addr 0 */ > + task_vma_iter_next_vma, /* use vma_next() with curr_vma */ > task_vma_iter_find_vma, /* use find_vma() to find next vma */ > }; > > @@ -400,24 +400,11 @@ task_vma_seq_get_next(struct bpf_iter_seq_task_vma_info *info) > > switch (op) { > case task_vma_iter_first_vma: > - curr_vma = curr_task->mm->mmap; > + curr_vma = find_vma(curr_task->mm, 0); > break; > case task_vma_iter_next_vma: > - curr_vma = curr_vma->vm_next; > - break; > case task_vma_iter_find_vma: > - /* We dropped mmap_lock so it is necessary to use find_vma > - * to find the next vma. This is similar to the mechanism > - * in show_smaps_rollup(). > - */ > - curr_vma = find_vma(curr_task->mm, info->prev_vm_end - 1); > - /* case 1) and 4.2) above just use curr_vma */ > - > - /* check for case 2) or case 4.1) above */ > - if (curr_vma && > - curr_vma->vm_start == info->prev_vm_start && > - curr_vma->vm_end == info->prev_vm_end) > - curr_vma = curr_vma->vm_next; > + curr_vma = find_vma(curr_task->mm, curr_vma->vm_end); Are you sure curr_vma is valid here and we can read its vm_end? Because I have no idea, but lots of doubts. > break; > } > if (!curr_vma) {
* Vlastimil Babka <vbabka@suse.cz> [220119 12:05]: > On 12/1/21 15:30, Liam Howlett wrote: > > From: "Liam R. Howlett" <Liam.Howlett@Oracle.com> > > > > Use vma_next() and remove reference to the start of the linked list > > > > Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com> > > --- > > kernel/bpf/task_iter.c | 21 ++++----------------- > > 1 file changed, 4 insertions(+), 17 deletions(-) > > > > diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c > > index b48750bfba5a..2d964743f1e6 100644 > > --- a/kernel/bpf/task_iter.c > > +++ b/kernel/bpf/task_iter.c > > @@ -299,8 +299,8 @@ struct bpf_iter_seq_task_vma_info { > > }; > > > > enum bpf_task_vma_iter_find_op { > > - task_vma_iter_first_vma, /* use mm->mmap */ > > - task_vma_iter_next_vma, /* use curr_vma->vm_next */ > > + task_vma_iter_first_vma, /* use find_vma() with addr 0 */ > > + task_vma_iter_next_vma, /* use vma_next() with curr_vma */ > > task_vma_iter_find_vma, /* use find_vma() to find next vma */ > > }; > > > > @@ -400,24 +400,11 @@ task_vma_seq_get_next(struct bpf_iter_seq_task_vma_info *info) > > > > switch (op) { > > case task_vma_iter_first_vma: > > - curr_vma = curr_task->mm->mmap; > > + curr_vma = find_vma(curr_task->mm, 0); > > break; > > case task_vma_iter_next_vma: > > - curr_vma = curr_vma->vm_next; > > - break; > > case task_vma_iter_find_vma: > > - /* We dropped mmap_lock so it is necessary to use find_vma > > - * to find the next vma. This is similar to the mechanism > > - * in show_smaps_rollup(). > > - */ > > - curr_vma = find_vma(curr_task->mm, info->prev_vm_end - 1); > > - /* case 1) and 4.2) above just use curr_vma */ > > - > > - /* check for case 2) or case 4.1) above */ > > - if (curr_vma && > > - curr_vma->vm_start == info->prev_vm_start && > > - curr_vma->vm_end == info->prev_vm_end) > > - curr_vma = curr_vma->vm_next; > > + curr_vma = find_vma(curr_task->mm, curr_vma->vm_end); > > Are you sure curr_vma is valid here and we can read its vm_end? Because I > have no idea, but lots of doubts. I am not sure. I'm going to drop this patch and take the more conservative but safer v3 version. > > > break; > > } > > if (!curr_vma) { > >
diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c index b48750bfba5a..2d964743f1e6 100644 --- a/kernel/bpf/task_iter.c +++ b/kernel/bpf/task_iter.c @@ -299,8 +299,8 @@ struct bpf_iter_seq_task_vma_info { }; enum bpf_task_vma_iter_find_op { - task_vma_iter_first_vma, /* use mm->mmap */ - task_vma_iter_next_vma, /* use curr_vma->vm_next */ + task_vma_iter_first_vma, /* use find_vma() with addr 0 */ + task_vma_iter_next_vma, /* use vma_next() with curr_vma */ task_vma_iter_find_vma, /* use find_vma() to find next vma */ }; @@ -400,24 +400,11 @@ task_vma_seq_get_next(struct bpf_iter_seq_task_vma_info *info) switch (op) { case task_vma_iter_first_vma: - curr_vma = curr_task->mm->mmap; + curr_vma = find_vma(curr_task->mm, 0); break; case task_vma_iter_next_vma: - curr_vma = curr_vma->vm_next; - break; case task_vma_iter_find_vma: - /* We dropped mmap_lock so it is necessary to use find_vma - * to find the next vma. This is similar to the mechanism - * in show_smaps_rollup(). - */ - curr_vma = find_vma(curr_task->mm, info->prev_vm_end - 1); - /* case 1) and 4.2) above just use curr_vma */ - - /* check for case 2) or case 4.1) above */ - if (curr_vma && - curr_vma->vm_start == info->prev_vm_start && - curr_vma->vm_end == info->prev_vm_end) - curr_vma = curr_vma->vm_next; + curr_vma = find_vma(curr_task->mm, curr_vma->vm_end); break; } if (!curr_vma) {