On Fri, 29 Jun 2018 11:17:52 -0700 Song Liu <songliubraving@xxxxxx> wrote: > Back in May, I sent patch similar to 02b75dc8160d: > > https://patchwork.kernel.org/patch/10416233/ (v1) > > This patch got positive feedback. However, I realized there is a problem, > that vma->vm_flags in khugepaged_enter_vma_merge() is stale. The separate > argument vm_flags contains the latest value. Therefore, it is > necessary to pass this vm_flags into hugepage_vma_check(). To fix this > problem, I resent v2 and v3 of the work: > > https://patchwork.kernel.org/patch/10419527/ (v2) > https://patchwork.kernel.org/patch/10433937/ (v3) > > To my surprise, after I thought we all agreed on v3 of the work. Yang's > patch, which is similar to correct looking (but wrong) v1, got applied. > So we still have the issue of stale vma->vm_flags. This patch fixes this > issue. Please apply. That's a ueful history lesson but most of it isn't relevant to this change. So I'd suggest this changelog: : khugepaged_enter_vma_merge() passes a stale vma->vm_flags to : hugepage_vma_check(). The argument vm_flags contains the latest value. : Therefore, it is necessary to pass this vm_flags into : hugepage_vma_check(). Also, please (as always) tell us the user-visible runtime effects of this bug so that others can decide which kernel(s) need the fix?
