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RDMA/siw: 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/20221116102659.70287-13-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Bernard Metzler <bmt@zurich.ibm.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 11:26:51 +01:00
committed by Andrew Morton
parent a9d0284033
commit 129e636fe9
1 changed files with 4 additions and 5 deletions
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9
drivers/infiniband/sw/siw/siw_mem.c
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@@ -368,7 +368,7 @@ struct siw_umem *siw_umem_get(u64 start, u64 len, bool writable)
struct mm_struct *mm_s;
u64 first_page_va;
unsigned long mlock_limit;
unsigned int foll_flags = FOLL_WRITE;
unsigned int foll_flags = FOLL_LONGTERM;
int num_pages, num_chunks, i, rv = 0;
if (!can_do_mlock())
@@ -391,8 +391,8 @@ struct siw_umem *siw_umem_get(u64 start, u64 len, bool writable)
mmgrab(mm_s);
if (!writable)
foll_flags |= FOLL_FORCE;
if (writable)
foll_flags |= FOLL_WRITE;
mmap_read_lock(mm_s);
@@ -423,8 +423,7 @@ struct siw_umem *siw_umem_get(u64 start, u64 len, bool writable)
while (nents) {
struct page **plist = &umem->page_chunk[i].plist[got];
rv = pin_user_pages(first_page_va, nents,
foll_flags | FOLL_LONGTERM,
rv = pin_user_pages(first_page_va, nents, foll_flags,
plist, NULL);
if (rv < 0)
goto out_sem_up;