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| author | Peter Xu <peterx@redhat.com> | 2022-04-28 23:16:16 -0700 |
|---|---|---|
| committer | akpm <akpm@linux-foundation.org> | 2022-04-28 23:16:16 -0700 |
| commit | ba91fb7dd03c4f463453f28af24851097a6547fb (patch) | |
| tree | a2025adccb8944ba5cf40b48464135ed071adad1 /include | |
| parent | 6fd3620b342861de9547ea01d28f664892ef51a1 (diff) | |
| download | lwn-ba91fb7dd03c4f463453f28af24851097a6547fb.tar.gz lwn-ba91fb7dd03c4f463453f28af24851097a6547fb.zip | |
include/linux/swapops.h: remove stub for non_swap_entry()
The stub for non_swap_entry() may not help much, because MAX_SWAPFILES has
already contained all the information to decide whether a swap entry is
real swap entry or pesudo ones (migrations, ...).
There can be some performance influences on non_swap_entry() with below
conditions all met:
!CONFIG_MIGRATION && !CONFIG_MEMORY_FAILURE && !CONFIG_DEVICE_PRIVATE
But that's definitely not the major config most machines will use, at the
meantime it's already in a slow path of swap entry (being parsed from a
swap pte), so IMHO it shouldn't be a major issue. Also according to the
analysis from Alistair, somehow the stub didn't do the job right [1].
To make the code cleaner, let's drop the stub.
[1] https://lore.kernel.org/lkml/8735ihbw6g.fsf@nvdebian.thelocal/
Note: the uffd-wp shmem & hugetlbfs series will need this patch to make
sure swap entries work as expected with below config as spotted by
Alistair:
!CONFIG_MIGRATION &&
!CONFIG_MEMORY_FAILURE &&
!CONFIG_DEVICE_PRIVATE &&
CONFIG_PTE_MARKER
(PS: this config should mostly never gonna happen, though, afaict..)
Link: https://lkml.kernel.org/r/20220413191147.66645-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/swapops.h | 8 |
1 files changed, 0 insertions, 8 deletions
diff --git a/include/linux/swapops.h b/include/linux/swapops.h index d356ab4047f7..5af852b68805 100644 --- a/include/linux/swapops.h +++ b/include/linux/swapops.h @@ -387,18 +387,10 @@ static inline void num_poisoned_pages_inc(void) } #endif -#if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION) || \ - defined(CONFIG_DEVICE_PRIVATE) static inline int non_swap_entry(swp_entry_t entry) { return swp_type(entry) >= MAX_SWAPFILES; } -#else -static inline int non_swap_entry(swp_entry_t entry) -{ - return 0; -} -#endif #endif /* CONFIG_MMU */ #endif /* _LINUX_SWAPOPS_H */ |