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powerpc/64s: Move serialize_against_pte_lookup() to hash_pgtable.c 

Originally,
commit fa4531f753 ("powerpc/mm: Don't send IPI to all cpus on THP updates")
introduced serialize_against_pte_lookup() call for both Radix and Hash.

However below commit fixed the race with Radix
commit 70cbc3cc78 ("mm: gup: fix the fast GUP race against THP collapse")

And therefore following commit removed the
serialize_against_pte_lookup() call from radix_pgtable.c
commit bedf034169
("powerpc/64s/radix: don't need to broadcast IPI for radix pmd collapse flush")

Now since serialize_against_pte_lookup() only gets called from
hash__pmdp_collapse_flush(), thus move the related functions to
hash_pgtable.c

Hence this patch:
- moves serialize_against_pte_lookup() from radix_pgtable.c to hash_pgtable.c
- removes the radix specific calls from do_serialize()
- renames do_serialize() to do_nothing().

There should not be any functionality change in this patch.

Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/a73ebe800a9be257329507703779f822363f8b2f.1773078178.git.ritesh.list@gmail.com
master
Ritesh Harjani (IBM) 2026-03-09 23:44:28 +05:30 committed by Madhavan Srinivasan
parent 4a342f3e6f
commit bf7c1497d2
3 changed files with 21 additions and 26 deletions
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1
arch/powerpc/include/asm/book3s/64/pgtable.h
View File

@ -1415,7 +1415,6 @@ static inline bool arch_needs_pgtable_deposit(void)
return false;
return true;
}
extern void serialize_against_pte_lookup(struct mm_struct *mm);
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

21
arch/powerpc/mm/book3s64/hash_pgtable.c
View File

@ -221,6 +221,27 @@ unsigned long hash__pmd_hugepage_update(struct mm_struct *mm, unsigned long addr
return old;
}
static void do_nothing(void *arg)
{
}
/*
* Serialize against __find_linux_pte() which does lock-less
* lookup in page tables with local interrupts disabled. For huge pages
* it casts pmd_t to pte_t. Since format of pte_t is different from
* pmd_t we want to prevent transit from pmd pointing to page table
* to pmd pointing to huge page (and back) while interrupts are disabled.
* We clear pmd to possibly replace it with page table pointer in
* different code paths. So make sure we wait for the parallel
* __find_linux_pte() to finish.
*/
static void serialize_against_pte_lookup(struct mm_struct *mm)
{
smp_mb();
smp_call_function_many(mm_cpumask(mm), do_nothing, mm, 1);
}
pmd_t hash__pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmdp)
{

25
arch/powerpc/mm/book3s64/pgtable.c
View File

@ -150,31 +150,6 @@ void set_pud_at(struct mm_struct *mm, unsigned long addr,
return set_pte_at_unchecked(mm, addr, pudp_ptep(pudp), pud_pte(pud));
}
static void do_serialize(void *arg)
{
/* We've taken the IPI, so try to trim the mask while here */
if (radix_enabled()) {
struct mm_struct *mm = arg;
exit_lazy_flush_tlb(mm, false);
}
}
/*
* Serialize against __find_linux_pte() which does lock-less
* lookup in page tables with local interrupts disabled. For huge pages
* it casts pmd_t to pte_t. Since format of pte_t is different from
* pmd_t we want to prevent transit from pmd pointing to page table
* to pmd pointing to huge page (and back) while interrupts are disabled.
* We clear pmd to possibly replace it with page table pointer in
* different code paths. So make sure we wait for the parallel
* __find_linux_pte() to finish.
*/
void serialize_against_pte_lookup(struct mm_struct *mm)
{
smp_mb();
smp_call_function_many(mm_cpumask(mm), do_serialize, mm, 1);
}
/*
* We use this to invalidate a pmdp entry before switching from a
* hugepte to regular pmd entry.