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Date: Wed, 26 Jan 2022 10:22:53 +0100 From: Vlastimil Babka <vbabka@...e.cz> To: Liam Howlett <liam.howlett@...cle.com> Cc: "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>, "linux-mm@...ck.org" <linux-mm@...ck.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Andrew Morton <akpm@...ux-foundation.org>, Song Liu <songliubraving@...com>, Davidlohr Bueso <dave@...olabs.net>, "Paul E . McKenney" <paulmck@...nel.org>, Matthew Wilcox <willy@...radead.org>, Laurent Dufour <ldufour@...ux.ibm.com>, David Rientjes <rientjes@...gle.com>, Axel Rasmussen <axelrasmussen@...gle.com>, Suren Baghdasaryan <surenb@...gle.com>, Rik van Riel <riel@...riel.com>, Peter Zijlstra <peterz@...radead.org>, Michel Lespinasse <walken.cr@...il.com>, Jerome Glisse <jglisse@...hat.com>, Minchan Kim <minchan@...gle.com>, Joel Fernandes <joelaf@...gle.com>, Rom Lemarchand <romlem@...gle.com> Subject: Re: [PATCH v4 55/66] mm/mempolicy: Use maple tree iterators instead of vma linked list On 1/26/22 03:48, Liam Howlett wrote: > * Vlastimil Babka <vbabka@...e.cz> [220120 06:58]: >> On 12/1/21 15:30, Liam Howlett wrote: >> > From: "Liam R. Howlett" <Liam.Howlett@...cle.com> >> > >> > Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org> >> > Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com> >> > --- >> > mm/mempolicy.c | 53 ++++++++++++++++++++++++++------------------------ >> > 1 file changed, 28 insertions(+), 25 deletions(-) >> > >> > diff --git a/mm/mempolicy.c b/mm/mempolicy.c >> > index 10e9c87260ed..0e2d918f4f30 100644 >> > --- a/mm/mempolicy.c >> > +++ b/mm/mempolicy.c >> > @@ -377,9 +377,10 @@ void mpol_rebind_task(struct task_struct *tsk, const nodemask_t *new) >> > void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new) >> > { >> > struct vm_area_struct *vma; >> > + MA_STATE(mas, &mm->mm_mt, 0, 0); >> >> VMA_ITERATOR? > > Yes, I will make this change. Thanks. > >> >> > >> > mmap_write_lock(mm); >> > - for (vma = mm->mmap; vma; vma = vma->vm_next) >> > + mas_for_each(&mas, vma, ULONG_MAX) >> > mpol_rebind_policy(vma->vm_policy, new); >> > mmap_write_unlock(mm); >> > } >> > @@ -652,7 +653,7 @@ static unsigned long change_prot_numa(struct vm_area_struct *vma, >> > static int queue_pages_test_walk(unsigned long start, unsigned long end, >> > struct mm_walk *walk) >> > { >> > - struct vm_area_struct *vma = walk->vma; >> > + struct vm_area_struct *next, *vma = walk->vma; >> > struct queue_pages *qp = walk->private; >> > unsigned long endvma = vma->vm_end; >> > unsigned long flags = qp->flags; >> > @@ -667,9 +668,10 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end, >> > /* hole at head side of range */ >> > return -EFAULT; >> > } >> > + next = find_vma(vma->vm_mm, vma->vm_end); >> > if (!(flags & MPOL_MF_DISCONTIG_OK) && >> > ((vma->vm_end < qp->end) && >> > - (!vma->vm_next || vma->vm_end < vma->vm_next->vm_start))) >> > + (!next || vma->vm_end < next->vm_start))) >> > /* hole at middle or tail of range */ >> > return -EFAULT; >> > >> > @@ -783,28 +785,24 @@ static int vma_replace_policy(struct vm_area_struct *vma, >> > static int mbind_range(struct mm_struct *mm, unsigned long start, >> > unsigned long end, struct mempolicy *new_pol) >> > { >> > - struct vm_area_struct *next; >> > + MA_STATE(mas, &mm->mm_mt, start - 1, start - 1); >> > struct vm_area_struct *prev; >> > struct vm_area_struct *vma; >> > int err = 0; >> > pgoff_t pgoff; >> > - unsigned long vmstart; >> > - unsigned long vmend; >> > - >> > - vma = find_vma(mm, start); >> > - VM_BUG_ON(!vma); >> > >> > - prev = vma->vm_prev; >> > - if (start > vma->vm_start) >> > - prev = vma; >> > + prev = mas_find_rev(&mas, 0); >> > + if (prev && (start < prev->vm_end)) >> > + vma = prev; >> > + else >> > + vma = mas_next(&mas, end - 1); >> > >> > - for (; vma && vma->vm_start < end; prev = vma, vma = next) { >> > - next = vma->vm_next; >> > - vmstart = max(start, vma->vm_start); >> > - vmend = min(end, vma->vm_end); >> > + do { >> > + unsigned long vmstart = max(start, vma->vm_start); >> > + unsigned long vmend = min(end, vma->vm_end); >> >> What if vma is null? Shouldn't this rather be a "for (; vma; vma = >> mas_next(...)" > > We have already found the vma above. AFAICS if the range intersects no vmas, we might have found a 'prev', but 'vma' might be NULL after the "vma = mas_next(&mas, end - 1);"?
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