On Tue 10-10-17 09:22:20, Xishi Qiu wrote: > On 2017/10/10 2:26, Michal Hocko wrote: > > > On Wed 27-09-17 13:51:09, Xishi Qiu wrote: > >> On 2017/9/26 19:00, Michal Hocko wrote: > >> > >>> On Tue 26-09-17 11:45:16, Vlastimil Babka wrote: > >>>> On 09/26/2017 11:22 AM, Xishi Qiu wrote: > >>>>> On 2017/9/26 17:13, Xishi Qiu wrote: > >>>>>>> This is still very fuzzy. What are you actually trying to achieve? > >>>>>> > >>>>>> I don't expect page fault any more after mlock. > >>>>>> > >>>>> > >>>>> Our apps is some thing like RT, and page-fault maybe cause a lot of time, > >>>>> e.g. lock, mem reclaim ..., so I use mlock and don't want page fault > >>>>> any more. > >>>> > >>>> Why does your app then have restricted mprotect when calling mlockall() > >>>> and only later adjusts the mprotect? > >>> > >>> Ahh, OK I see what is goging on. So you have PROT_NONE vma at the time > >>> mlockall and then later mprotect it something else and want to fault all > >>> that memory at the mprotect time? > >>> > >>> So basically to do > >>> --- > >>> diff --git a/mm/mprotect.c b/mm/mprotect.c > >>> index 6d3e2f082290..b665b5d1c544 100644 > >>> --- a/mm/mprotect.c > >>> +++ b/mm/mprotect.c > >>> @@ -369,7 +369,7 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev, > >>> * Private VM_LOCKED VMA becoming writable: trigger COW to avoid major > >>> * fault on access. > >>> */ > >>> - if ((oldflags & (VM_WRITE | VM_SHARED | VM_LOCKED)) == VM_LOCKED && > >>> + if ((oldflags & (VM_WRITE | VM_LOCKED)) == VM_LOCKED && > >>> (newflags & VM_WRITE)) { > >>> populate_vma_page_range(vma, start, end, NULL); > >>> } > >>> > >> > >> Hi Michal, > >> > >> My kernel is v3.10, and I missed this code, thank you reminding me. > > > > I guess I didn't get your answer. Does the above diff resolves your > > problem? > > Hi Michal, > > This upstream patch 36f881883c57941bb32d25cea6524f9612ab5a2c has already > resolve my problem, thank you for your attention. OK, fair enough. But is does it make sense to extend this behavior to shared mappings as well? -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>