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Peter Anvin" , Andrew Morton , Shuah Khan , Kees Cook , "Aneesh Kumar K.V" , Peter Zijlstra , Arnd Bergmann , Sami Tolvanen , Masahiro Yamada , Frederic Weisbecker , Krzysztof Kozlowski , Hassan Naveed , Christian Brauner , Stephen Boyd , Mark Rutland , Mark Brown , Mike Rapoport , Gavin Shan , Chris von Recklinghausen , Jia He , Zhenyu Ye , John Hubbard , Sandipan Das , Dave Hansen , Ralph Campbell , Ram Pai , "Kirill A. Shutemov" , William Kucharski , Brian Geffon , Mina Almasry , Masami Hiramatsu , SeongJae Park , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Android needs to move large memory regions for garbage collection. Optimize mremap for >=3D 1GB-sized regions by moving at the PUD/PGD level if the source and destination addresses are PUD-aligned. For CONFIG_PGTABLE_LEVELS =3D=3D 3, moving at the PUD level in effect moves PGD entries, since the PUD entry is =E2=80=9Cfolded back=E2=80=9D onto the = PGD entry. Add HAVE_MOVE_PUD so that architectures where moving at the PUD level isn't supported/tested can turn this off by not selecting the config. Signed-off-by: Kalesh Singh --- arch/Kconfig | 7 + arch/arm64/include/asm/pgtable.h | 1 + mm/mremap.c | 211 ++++++++++++++++++++++++++----- 3 files changed, 189 insertions(+), 30 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index af14a567b493..5eabaa00bf9b 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -602,6 +602,13 @@ config HAVE_IRQ_TIME_ACCOUNTING Archs need to ensure they use a high enough resolution clock to support irq time accounting and then call enable_sched_clock_irqtime(). =20 +config HAVE_MOVE_PUD + bool + help + Architectures that select this are able to move page tables at the + PUD level. If there are only 3 page table levels, the move effectively + happens at the PGD level. + config HAVE_MOVE_PMD bool help diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgta= ble.h index d5d3fbe73953..8848125e3024 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -415,6 +415,7 @@ static inline pmd_t pmd_mkdevmap(pmd_t pmd) #define pfn_pud(pfn,prot) __pud(__phys_to_pud_val((phys_addr_t)(pfn) << PA= GE_SHIFT) | pgprot_val(prot)) =20 #define set_pmd_at(mm, addr, pmdp, pmd) set_pte_at(mm, addr, (pte_t *)pmdp= , pmd_pte(pmd)) +#define set_pud_at(mm, addr, pudp, pud) set_pte_at(mm, addr, (pte_t *)pudp= , pud_pte(pud)) =20 #define __p4d_to_phys(p4d) __pte_to_phys(p4d_pte(p4d)) #define __phys_to_p4d_val(phys) __phys_to_pte_val(phys) diff --git a/mm/mremap.c b/mm/mremap.c index 138abbae4f75..a5a1440bd366 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -249,14 +249,167 @@ static bool move_normal_pmd(struct vm_area_struct *v= ma, unsigned long old_addr, =20 return true; } +#else +static inline bool move_normal_pmd(struct vm_area_struct *vma, unsigned lo= ng old_addr, + unsigned long new_addr, pmd_t *old_pmd, pmd_t *new_pmd) +{ + return false; +} #endif =20 +#ifdef CONFIG_HAVE_MOVE_PUD +static pud_t *get_old_pud(struct mm_struct *mm, unsigned long addr) +{ + pgd_t *pgd; + p4d_t *p4d; + pud_t *pud; + + pgd =3D pgd_offset(mm, addr); + if (pgd_none_or_clear_bad(pgd)) + return NULL; + + p4d =3D p4d_offset(pgd, addr); + if (p4d_none_or_clear_bad(p4d)) + return NULL; + + pud =3D pud_offset(p4d, addr); + if (pud_none_or_clear_bad(pud)) + return NULL; + + return pud; +} + +static pud_t *alloc_new_pud(struct mm_struct *mm, struct vm_area_struct *v= ma, + unsigned long addr) +{ + pgd_t *pgd; + p4d_t *p4d; + pud_t *pud; + + pgd =3D pgd_offset(mm, addr); + p4d =3D p4d_alloc(mm, pgd, addr); + if (!p4d) + return NULL; + pud =3D pud_alloc(mm, p4d, addr); + if (!pud) + return NULL; + + return pud; +} + +static bool move_normal_pud(struct vm_area_struct *vma, unsigned long old_= addr, + unsigned long new_addr, pud_t *old_pud, pud_t *new_pud) +{ + spinlock_t *old_ptl, *new_ptl; + struct mm_struct *mm =3D vma->vm_mm; + pud_t pud; + + /* + * The destination pud shouldn't be established, free_pgtables() + * should have released it. + */ + if (WARN_ON_ONCE(!pud_none(*new_pud))) + return false; + + /* + * We don't have to worry about the ordering of src and dst + * ptlocks because exclusive mmap_lock prevents deadlock. + */ + old_ptl =3D pud_lock(vma->vm_mm, old_pud); + new_ptl =3D pud_lockptr(mm, new_pud); + if (new_ptl !=3D old_ptl) + spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); + + /* Clear the pud */ + pud =3D *old_pud; + pud_clear(old_pud); + + VM_BUG_ON(!pud_none(*new_pud)); + + /* Set the new pud */ + set_pud_at(mm, new_addr, new_pud, pud); + flush_tlb_range(vma, old_addr, old_addr + PUD_SIZE); + if (new_ptl !=3D old_ptl) + spin_unlock(new_ptl); + spin_unlock(old_ptl); + + return true; +} +#else +static inline bool move_normal_pud(struct vm_area_struct *vma, unsigned lo= ng old_addr, + unsigned long new_addr, pud_t *old_pud, pud_t *new_pud) +{ + return false; +} +#endif + +enum pgt_entry { + NORMAL_PMD, + HPAGE_PMD, + NORMAL_PUD, +}; + +/* + * Returns an extent of the corresponding size for the pgt_entry specified= if valid. + * Else returns a smaller extent bounded by the end of the source and dest= ination + * pgt_entry. Returns 0 if an invalid pgt_entry is specified. + */ +static unsigned long get_extent(enum pgt_entry entry, unsigned long old_ad= dr, + unsigned long old_end, unsigned long new_addr) +{ + unsigned long next, extent, mask, size; + + if (entry =3D=3D NORMAL_PMD || entry =3D=3D HPAGE_PMD) { + mask =3D PMD_MASK; + size =3D PMD_SIZE; + } else if (entry =3D=3D NORMAL_PUD) { + mask =3D PUD_MASK; + size =3D PUD_SIZE; + } else + return 0; + + next =3D (old_addr + size) & mask; + /* even if next overflowed, extent below will be ok */ + extent =3D (next > old_end) ? old_end - old_addr : next - old_addr; + next =3D (new_addr + size) & mask; + if (extent > next - new_addr) + extent =3D next - new_addr; + return extent; +} + +/* + * Attempts to speedup the move by moving entry at the level corresponding= to + * pgt_entry. Returns true if the move was successful, else false. + */ +static bool move_pgt_entry(enum pgt_entry entry, struct vm_area_struct *vm= a, + unsigned long old_addr, unsigned long new_addr, void *old_entry, + void *new_entry, bool need_rmap_locks) +{ + bool moved =3D false; + + /* See comment in move_ptes() */ + if (need_rmap_locks) + take_rmap_locks(vma); + if (entry =3D=3D NORMAL_PMD) + moved =3D move_normal_pmd(vma, old_addr, new_addr, old_entry, new_entry= ); + else if (entry =3D=3D NORMAL_PUD) + moved =3D move_normal_pud(vma, old_addr, new_addr, old_entry, new_entry= ); + else if (entry =3D=3D HPAGE_PMD) + moved =3D move_huge_pmd(vma, old_addr, new_addr, old_entry, new_entry); + else + WARN_ON_ONCE(1); + if (need_rmap_locks) + drop_rmap_locks(vma); + + return moved; +} + unsigned long move_page_tables(struct vm_area_struct *vma, unsigned long old_addr, struct vm_area_struct *new_vma, unsigned long new_addr, unsigned long len, bool need_rmap_locks) { - unsigned long extent, next, old_end; + unsigned long extent, old_end; struct mmu_notifier_range range; pmd_t *old_pmd, *new_pmd; =20 @@ -269,14 +422,27 @@ unsigned long move_page_tables(struct vm_area_struct = *vma, =20 for (; old_addr < old_end; old_addr +=3D extent, new_addr +=3D extent) { cond_resched(); - next =3D (old_addr + PMD_SIZE) & PMD_MASK; - /* even if next overflowed, extent below will be ok */ - extent =3D next - old_addr; - if (extent > old_end - old_addr) - extent =3D old_end - old_addr; - next =3D (new_addr + PMD_SIZE) & PMD_MASK; - if (extent > next - new_addr) - extent =3D next - new_addr; +#ifdef CONFIG_HAVE_MOVE_PUD + /* + * If extent is PUD-sized try to speed up the move by moving at the + * PUD level if possible. + */ + extent =3D get_extent(NORMAL_PUD, old_addr, old_end, new_addr); + if (extent =3D=3D PUD_SIZE) { + pud_t *old_pud, *new_pud; + + old_pud =3D get_old_pud(vma->vm_mm, old_addr); + if (!old_pud) + continue; + new_pud =3D alloc_new_pud(vma->vm_mm, vma, new_addr); + if (!new_pud) + break; + if (move_pgt_entry(NORMAL_PUD, vma, old_addr, new_addr, + old_pud, new_pud, need_rmap_locks)) + continue; + } +#endif + extent =3D get_extent(NORMAL_PMD, old_addr, old_end, new_addr); old_pmd =3D get_old_pmd(vma->vm_mm, old_addr); if (!old_pmd) continue; @@ -284,18 +450,10 @@ unsigned long move_page_tables(struct vm_area_struct = *vma, if (!new_pmd) break; if (is_swap_pmd(*old_pmd) || pmd_trans_huge(*old_pmd) || pmd_devmap(*old= _pmd)) { - if (extent =3D=3D HPAGE_PMD_SIZE) { - bool moved; - /* See comment in move_ptes() */ - if (need_rmap_locks) - take_rmap_locks(vma); - moved =3D move_huge_pmd(vma, old_addr, new_addr, - old_pmd, new_pmd); - if (need_rmap_locks) - drop_rmap_locks(vma); - if (moved) - continue; - } + if (extent =3D=3D HPAGE_PMD_SIZE && + move_pgt_entry(HPAGE_PMD, vma, old_addr, new_addr, old_pmd, + new_pmd, need_rmap_locks)) + continue; split_huge_pmd(vma, old_pmd, old_addr); if (pmd_trans_unstable(old_pmd)) continue; @@ -305,15 +463,8 @@ unsigned long move_page_tables(struct vm_area_struct *= vma, * If the extent is PMD-sized, try to speed the move by * moving at the PMD level if possible. */ - bool moved; - - if (need_rmap_locks) - take_rmap_locks(vma); - moved =3D move_normal_pmd(vma, old_addr, new_addr, - old_pmd, new_pmd); - if (need_rmap_locks) - drop_rmap_locks(vma); - if (moved) + if (move_pgt_entry(NORMAL_PMD, vma, old_addr, new_addr, old_pmd, + new_pmd, need_rmap_locks)) continue; #endif } --=20 2.28.0.709.gb0816b6eb0-goog