Messages in this thread | | | Subject | Re: [PATCH 3/5] mm/migrate.c: fix potential indeterminate pte entry in migrate_vma_insert_page() | From | Miaohe Lin <> | Date | Tue, 23 Mar 2021 19:28:32 +0800 |
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On 2021/3/23 19:07, Alistair Popple wrote: > On Tuesday, 23 March 2021 9:26:43 PM AEDT David Hildenbrand wrote: >> On 20.03.21 10:36, Miaohe Lin wrote: >>> If the zone device page does not belong to un-addressable device memory, >>> the variable entry will be uninitialized and lead to indeterminate pte >>> entry ultimately. Fix this unexpectant case and warn about it. >> >> s/unexpectant/unexpected/ >> >>> >>> Fixes: df6ad69838fc ("mm/device-public-memory: device memory cache > coherent with CPU") >>> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> >>> --- >>> mm/migrate.c | 7 +++++++ >>> 1 file changed, 7 insertions(+) >>> >>> diff --git a/mm/migrate.c b/mm/migrate.c >>> index 20a3bf75270a..271081b014cb 100644 >>> --- a/mm/migrate.c >>> +++ b/mm/migrate.c >>> @@ -2972,6 +2972,13 @@ static void migrate_vma_insert_page(struct > migrate_vma *migrate, >>> >>> swp_entry = make_device_private_entry(page, vma->vm_flags & > VM_WRITE); >>> entry = swp_entry_to_pte(swp_entry); >>> + } else { >>> + /* >>> + * For now we only support migrating to un-addressable >>> + * device memory. >>> + */ >>> + WARN_ON(1); >>> + goto abort; >> >> Fix it by crashing the kernel with panic_on_warn? :) >> >> If this case can actual happen, than no WARN_ON() - rather a >> pr_warn_once(). If this case cannot happen, why do we even care (it's >> not a fix then)? > > There is also already a check for this case in migrate_vma_pages(). The > problem is it happens after the call to migrate_vma_insert_page(). I wonder if > instead it would be better just to move the existing check to before that > call? >
Yes, sounds good! Many thanks for your advice! :)
> > > . >
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