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Message-ID: <85a68c56-7cce-ef98-7aa6-c68eabf3fa0b@redhat.com> Date: Tue, 1 Mar 2022 17:32:24 +0100 From: David Hildenbrand <david@...hat.com> To: Felix Kuehling <felix.kuehling@....com>, Alex Sierra <alex.sierra@....com>, jgg@...dia.com Cc: rcampbell@...dia.com, willy@...radead.org, apopple@...dia.com, dri-devel@...ts.freedesktop.org, linux-xfs@...r.kernel.org, linux-mm@...ck.org, jglisse@...hat.com, amd-gfx@...ts.freedesktop.org, akpm@...ux-foundation.org, linux-ext4@...r.kernel.org, hch@....de Subject: Re: [PATCH] mm: split vm_normal_pages for LRU and non-LRU handling On 01.03.22 17:30, Felix Kuehling wrote: > Am 2022-03-01 um 11:22 schrieb David Hildenbrand: >>>>> if (PageReserved(page)) >>>>> diff --git a/mm/migrate.c b/mm/migrate.c >>>>> index c31d04b46a5e..17d049311b78 100644 >>>>> --- a/mm/migrate.c >>>>> +++ b/mm/migrate.c >>>>> @@ -1614,7 +1614,7 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr, >>>>> goto out; >>>>> >>>>> /* FOLL_DUMP to ignore special (like zero) pages */ >>>>> - follflags = FOLL_GET | FOLL_DUMP; >>>>> + follflags = FOLL_GET | FOLL_DUMP | FOLL_LRU; >>>>> page = follow_page(vma, addr, follflags); >>>> Why wouldn't we want to dump DEVICE_COHERENT pages? This looks wrong. >>> This function later calls isolate_lru_page, which is something you can't >>> do with a device page. >>> >> Then, that code might require care instead. We most certainly don't want >> to have random memory holes in a dump just because some anonymous memory >> was migrated to DEVICE_COHERENT. > I don't think this code is for core dumps. The call chain I see is > > SYSCALL_DEFINE6(move_pages, ...) -> kernel_move_pages -> do_pages_move > -> add_page_for_migration > Ah, sorry, I got mislead by FOLL_DUMP and thought we'd be in get_dump_page() . As you said, nothing to do. -- Thanks, David / dhildenb
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