| Message ID | 20190301004903.89514-1-cai@lca.pw (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/hugepages: fix "orig_pud" set but not used | expand |
On Thu, 28 Feb 2019 19:49:03 -0500 Qian Cai <cai@lca.pw> wrote: > The commit a00cc7d9dd93 ("mm, x86: add support for PUD-sized transparent > hugepages") introduced pudp_huge_get_and_clear_full() but no one uses > its return code, so just make it void. > > mm/huge_memory.c: In function 'zap_huge_pud': > mm/huge_memory.c:1982:8: warning: variable 'orig_pud' set but not used > [-Wunused-but-set-variable] > pud_t orig_pud; > ^~~~~~~~ > > ... > > --- a/include/asm-generic/pgtable.h > +++ b/include/asm-generic/pgtable.h > @@ -167,11 +167,11 @@ static inline pmd_t pmdp_huge_get_and_clear_full(struct mm_struct *mm, > #endif > > #ifndef __HAVE_ARCH_PUDP_HUGE_GET_AND_CLEAR_FULL > -static inline pud_t pudp_huge_get_and_clear_full(struct mm_struct *mm, > - unsigned long address, pud_t *pudp, > - int full) > +static inline void pudp_huge_get_and_clear_full(struct mm_struct *mm, > + unsigned long address, > + pud_t *pudp, int full) > { > - return pudp_huge_get_and_clear(mm, address, pudp); > + pudp_huge_get_and_clear(mm, address, pudp); > } Not sure this is a good change. Future callers might want that return value. > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -1979,7 +1979,6 @@ spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) > int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, > pud_t *pud, unsigned long addr) > { > - pud_t orig_pud; > spinlock_t *ptl; > > ptl = __pud_trans_huge_lock(pud, vma); > @@ -1991,8 +1990,7 @@ int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, > * pgtable_trans_huge_withdraw after finishing pudp related > * operations. > */ > - orig_pud = pudp_huge_get_and_clear_full(tlb->mm, addr, pud, > - tlb->fullmm); > + pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); In fact this code perhaps should be passing orig_pud into pudp_huge_get_and_clear_full(). That could depend on what future per-arch implementations of pudp_huge_get_and_clear_full() choose to do. Anyway, I'll await Matthew's feedback.
On Fri, Mar 01, 2019 at 01:09:51PM -0800, Andrew Morton wrote: > On Thu, 28 Feb 2019 19:49:03 -0500 Qian Cai <cai@lca.pw> wrote: > > > The commit a00cc7d9dd93 ("mm, x86: add support for PUD-sized transparent > > hugepages") introduced pudp_huge_get_and_clear_full() but no one uses > > its return code, so just make it void. > > > > mm/huge_memory.c: In function 'zap_huge_pud': > > mm/huge_memory.c:1982:8: warning: variable 'orig_pud' set but not used > > [-Wunused-but-set-variable] > > pud_t orig_pud; > > ^~~~~~~~ > > > > ... > > > > --- a/include/asm-generic/pgtable.h > > +++ b/include/asm-generic/pgtable.h > > @@ -167,11 +167,11 @@ static inline pmd_t pmdp_huge_get_and_clear_full(struct mm_struct *mm, > > #endif > > > > #ifndef __HAVE_ARCH_PUDP_HUGE_GET_AND_CLEAR_FULL > > -static inline pud_t pudp_huge_get_and_clear_full(struct mm_struct *mm, > > - unsigned long address, pud_t *pudp, > > - int full) > > +static inline void pudp_huge_get_and_clear_full(struct mm_struct *mm, > > + unsigned long address, > > + pud_t *pudp, int full) > > { > > - return pudp_huge_get_and_clear(mm, address, pudp); > > + pudp_huge_get_and_clear(mm, address, pudp); > > } > > Not sure this is a good change. Future callers might want that return > value. > > > --- a/mm/huge_memory.c > > +++ b/mm/huge_memory.c > > @@ -1979,7 +1979,6 @@ spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) > > int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, > > pud_t *pud, unsigned long addr) > > { > > - pud_t orig_pud; > > spinlock_t *ptl; > > > > ptl = __pud_trans_huge_lock(pud, vma); > > @@ -1991,8 +1990,7 @@ int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, > > * pgtable_trans_huge_withdraw after finishing pudp related > > * operations. > > */ > > - orig_pud = pudp_huge_get_and_clear_full(tlb->mm, addr, pud, > > - tlb->fullmm); > > + pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); > > In fact this code perhaps should be passing orig_pud into > pudp_huge_get_and_clear_full(). That could depend on what future > per-arch implementations of pudp_huge_get_and_clear_full() choose to > do. > > Anyway, I'll await Matthew's feedback. I'm not sure it's wise to diverge from pmdp_huge_get_and_clear_full() which does return the orig_pud. I agree we don't currently use it, so maybe we should just change zap_huge_pud() to not assign the return value from pudp_huge_get_and_clear_full()?
diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index 05e61e6c843f..17b789557afe 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -167,11 +167,11 @@ static inline pmd_t pmdp_huge_get_and_clear_full(struct mm_struct *mm, #endif #ifndef __HAVE_ARCH_PUDP_HUGE_GET_AND_CLEAR_FULL -static inline pud_t pudp_huge_get_and_clear_full(struct mm_struct *mm, - unsigned long address, pud_t *pudp, - int full) +static inline void pudp_huge_get_and_clear_full(struct mm_struct *mm, + unsigned long address, + pud_t *pudp, int full) { - return pudp_huge_get_and_clear(mm, address, pudp); + pudp_huge_get_and_clear(mm, address, pudp); } #endif #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ diff --git a/mm/huge_memory.c b/mm/huge_memory.c index faf357eaf0ce..9f57a1173e6a 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1979,7 +1979,6 @@ spinlock_t *__pud_trans_huge_lock(pud_t *pud, struct vm_area_struct *vma) int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, pud_t *pud, unsigned long addr) { - pud_t orig_pud; spinlock_t *ptl; ptl = __pud_trans_huge_lock(pud, vma); @@ -1991,8 +1990,7 @@ int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, * pgtable_trans_huge_withdraw after finishing pudp related * operations. */ - orig_pud = pudp_huge_get_and_clear_full(tlb->mm, addr, pud, - tlb->fullmm); + pudp_huge_get_and_clear_full(tlb->mm, addr, pud, tlb->fullmm); tlb_remove_pud_tlb_entry(tlb, pud, addr); if (vma_is_dax(vma)) { spin_unlock(ptl);
The commit a00cc7d9dd93 ("mm, x86: add support for PUD-sized transparent hugepages") introduced pudp_huge_get_and_clear_full() but no one uses its return code, so just make it void. mm/huge_memory.c: In function 'zap_huge_pud': mm/huge_memory.c:1982:8: warning: variable 'orig_pud' set but not used [-Wunused-but-set-variable] pud_t orig_pud; ^~~~~~~~ Signed-off-by: Qian Cai <cai@lca.pw> --- include/asm-generic/pgtable.h | 8 ++++---- mm/huge_memory.c | 4 +--- 2 files changed, 5 insertions(+), 7 deletions(-)