From: Minchan Kim <minchan@kernel.org>
To: willy@infradead.org, hughd@google.com, kirill@shutemov.name
Cc: linux-mm <linux-mm@kvack.org>
Subject: THP handling with driver compound page on fault
Date: Fri, 29 Jan 2021 16:13:07 -0800 [thread overview]
Message-ID: <YBSkk0sZOQxgDNSO@google.com> (raw)
Hi Folks,
A custom driver overrides (vm_operations_struct.fault) and map their
compound page(__GFP_COMP) to page table on userprocess on demand.
Here problem is
page fault occur:
__do_fault
vma->vm_ops->fault <- driver returns their compould page
finish_fault
alloc_set_pte
PageTransCompound(page)
do_set_pmd
map the page as THP page
Since it's not a THP page, system goes random crash after a while due to
conflict of VM THP handling with the driver compound page handling.
Even though it happens in old kernel with backporting THP pagecache,
I think it's still valid on recent kernel.
What's the best way to fix it? Driver don't do that or VM need to
deal with it?
Thank you.
next reply other threads:[~2021-01-30 0:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-30 0:13 Minchan Kim [this message]
2021-01-30 1:00 ` THP handling with driver compound page on fault Matthew Wilcox
2021-01-30 1:22 ` Minchan Kim
2021-01-30 1:28 ` Matthew Wilcox
2021-01-30 1:49 ` Minchan Kim
2021-01-30 2:09 ` Matthew Wilcox
2021-01-30 2:40 ` Minchan Kim
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