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RDMA/umem: 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/20221116102659.70287-11-david@redhat.com
Tested-by: Leon Romanovsky <leonro@nvidia.com>	[over mlx4 and mlx5]
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.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 11:26:49 +01:00 committed by Andrew Morton
parent 84209e87c6
commit b40656aa7d
1 changed files with 4 additions and 4 deletions
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8
drivers/infiniband/core/umem.c
View file

@ -156,7 +156,7 @@ struct ib_umem *ib_umem_get(struct ib_device *device, unsigned long addr,
struct mm_struct *mm;
unsigned long npages;
int pinned, ret;
unsigned int gup_flags = FOLL_WRITE;
unsigned int gup_flags = FOLL_LONGTERM;
/*
* If the combination of the addr and size requested for this memory
@ -210,8 +210,8 @@ struct ib_umem *ib_umem_get(struct ib_device *device, unsigned long addr,
cur_base = addr & PAGE_MASK;
if (!umem->writable)
gup_flags |= FOLL_FORCE;
if (umem->writable)
gup_flags |= FOLL_WRITE;
while (npages) {
cond_resched();
@ -219,7 +219,7 @@ struct ib_umem *ib_umem_get(struct ib_device *device, unsigned long addr,
min_t(unsigned long, npages,
PAGE_SIZE /
sizeof(struct page *)),
gup_flags | FOLL_LONGTERM, page_list);
gup_flags, page_list);
if (pinned < 0) {
ret = pinned;
goto umem_release;