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RDMA/usnic: remove FOLL_FORCE usage

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GUP now supports reliable R/O long-term pinning in COW mappings, such
that we break COW early. MAP_SHARED VMAs only use the shared zeropage so
far in one corner case (DAXFS file with holes), which can be ignored
because GUP does not support long-term pinning in fsdax (see
check_vma_flags()).

Consequently, FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM is no longer required
for reliable R/O long-term pinning: FOLL_LONGTERM is sufficient. So stop
using FOLL_FORCE, which is really only for ptrace access.

Link: https://lkml.kernel.org/r/20221116102659.70287-12-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Christian Benvenuti <benve@cisco.com>
Cc: Nelson Escobar <neescoba@cisco.com>
Cc: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand 2022-11-16 11:26:50 +01:00 committed by Andrew Morton
parent b40656aa7d
commit a9d0284033
1 changed files with 4 additions and 5 deletions
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9
drivers/infiniband/hw/usnic/usnic_uiom.c
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@ -85,6 +85,7 @@ static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable,
int dmasync, struct usnic_uiom_reg *uiomr)
{
struct list_head *chunk_list = &uiomr->chunk_list;
unsigned int gup_flags = FOLL_LONGTERM;
struct page **page_list;
struct scatterlist *sg;
struct usnic_uiom_chunk *chunk;
@ -96,7 +97,6 @@ static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable,
int off;
int i;
dma_addr_t pa;
unsigned int gup_flags;
struct mm_struct *mm;
/*
@ -131,8 +131,8 @@ static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable,
goto out;
}
gup_flags = FOLL_WRITE;
gup_flags |= (writable) ? 0 : FOLL_FORCE;
if (writable)
gup_flags |= FOLL_WRITE;
cur_base = addr & PAGE_MASK;
ret = 0;
@ -140,8 +140,7 @@ static int usnic_uiom_get_pages(unsigned long addr, size_t size, int writable,
ret = pin_user_pages(cur_base,
min_t(unsigned long, npages,
PAGE_SIZE / sizeof(struct page *)),
gup_flags | FOLL_LONGTERM,
page_list, NULL);
gup_flags, page_list, NULL);
if (ret < 0)
goto out;