From 0fbebed682ff2788dee58e8d7f7dda46e33aa10b Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Tue, 19 Feb 2013 22:34:10 -0800 Subject: [PATCH] sparc64: Fix tsb_grow() in atomic context. If our first THP installation for an MM is via the set_pmd_at() done during khugepaged's collapsing we'll end up in tsb_grow() trying to do a GFP_KERNEL allocation with several locks held. Simply using GFP_ATOMIC in this situation is not the best option because we really can't have this fail, so we'd really like to keep this an order 0 GFP_KERNEL allocation if possible. Also, doing the TSB allocation from khugepaged is a really bad idea because we'll allocate it potentially from the wrong NUMA node in that context. So what we do is defer the hugepage TSB allocation until the first TLB miss we take on a hugepage. This is slightly tricky because we have to handle two unusual cases: 1) Taking the first hugepage TLB miss in the window trap handler. We'll call the winfix_trampoline when that is detected. 2) An initial TSB allocation via TLB miss races with a hugetlb fault on another cpu running the same MM. We handle this by unconditionally loading the TSB we see into the current cpu even if it's non-NULL at hugetlb_setup time. Reported-by: Meelis Roos Signed-off-by: David S. Miller --- arch/sparc/include/asm/hugetlb.h | 1 - arch/sparc/include/asm/page_64.h | 4 ++-- arch/sparc/kernel/tsb.S | 39 ++++++++++++++++++++++++++++---- arch/sparc/mm/fault_64.c | 9 ++++++-- arch/sparc/mm/init_64.c | 24 ++++++++++++++++---- arch/sparc/mm/tlb.c | 11 +++++++-- 6 files changed, 72 insertions(+), 16 deletions(-) diff --git a/arch/sparc/include/asm/hugetlb.h b/arch/sparc/include/asm/hugetlb.h index 9661e9bc7bb6..7eb57d245044 100644 --- a/arch/sparc/include/asm/hugetlb.h +++ b/arch/sparc/include/asm/hugetlb.h @@ -12,7 +12,6 @@ pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr, static inline void hugetlb_prefault_arch_hook(struct mm_struct *mm) { - hugetlb_setup(mm); } static inline int is_hugepage_only_range(struct mm_struct *mm, diff --git a/arch/sparc/include/asm/page_64.h b/arch/sparc/include/asm/page_64.h index 4b39f74d6ca0..e15538899f3d 100644 --- a/arch/sparc/include/asm/page_64.h +++ b/arch/sparc/include/asm/page_64.h @@ -27,8 +27,8 @@ #ifndef __ASSEMBLY__ #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE) -struct mm_struct; -extern void hugetlb_setup(struct mm_struct *mm); +struct pt_regs; +extern void hugetlb_setup(struct pt_regs *regs); #endif #define WANT_PAGE_VIRTUAL diff --git a/arch/sparc/kernel/tsb.S b/arch/sparc/kernel/tsb.S index d4bdc7a62375..a313e4a9399b 100644 --- a/arch/sparc/kernel/tsb.S +++ b/arch/sparc/kernel/tsb.S @@ -136,12 +136,43 @@ tsb_miss_page_table_walk_sun4v_fastpath: nop /* It is a huge page, use huge page TSB entry address we - * calculated above. + * calculated above. If the huge page TSB has not been + * allocated, setup a trap stack and call hugetlb_setup() + * to do so, then return from the trap to replay the TLB + * miss. + * + * This is necessary to handle the case of transparent huge + * pages where we don't really have a non-atomic context + * in which to allocate the hugepage TSB hash table. When + * the 'mm' faults in the hugepage for the first time, we + * thus handle it here. This also makes sure that we can + * allocate the TSB hash table on the correct NUMA node. */ TRAP_LOAD_TRAP_BLOCK(%g7, %g2) - ldx [%g7 + TRAP_PER_CPU_TSB_HUGE_TEMP], %g2 - cmp %g2, -1 - movne %xcc, %g2, %g1 + ldx [%g7 + TRAP_PER_CPU_TSB_HUGE_TEMP], %g1 + cmp %g1, -1 + bne,pt %xcc, 60f + nop + +661: rdpr %pstate, %g5 + wrpr %g5, PSTATE_AG | PSTATE_MG, %pstate + .section .sun4v_2insn_patch, "ax" + .word 661b + SET_GL(1) + nop + .previous + + rdpr %tl, %g3 + cmp %g3, 1 + bne,pn %xcc, winfix_trampoline + nop + ba,pt %xcc, etrap + rd %pc, %g7 + call hugetlb_setup + add %sp, PTREGS_OFF, %o0 + ba,pt %xcc, rtrap + nop + 60: #endif diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c index 097aee763af3..5062ff389e83 100644 --- a/arch/sparc/mm/fault_64.c +++ b/arch/sparc/mm/fault_64.c @@ -472,8 +472,13 @@ asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs) #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE) mm_rss = mm->context.huge_pte_count; if (unlikely(mm_rss > - mm->context.tsb_block[MM_TSB_HUGE].tsb_rss_limit)) - tsb_grow(mm, MM_TSB_HUGE, mm_rss); + mm->context.tsb_block[MM_TSB_HUGE].tsb_rss_limit)) { + if (mm->context.tsb_block[MM_TSB_HUGE].tsb) + tsb_grow(mm, MM_TSB_HUGE, mm_rss); + else + hugetlb_setup(regs); + + } #endif return; diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c index 0d0bc392c35f..82bbf048a5b0 100644 --- a/arch/sparc/mm/init_64.c +++ b/arch/sparc/mm/init_64.c @@ -2718,14 +2718,28 @@ static void context_reload(void *__data) load_secondary_context(mm); } -void hugetlb_setup(struct mm_struct *mm) +void hugetlb_setup(struct pt_regs *regs) { - struct tsb_config *tp = &mm->context.tsb_block[MM_TSB_HUGE]; + struct mm_struct *mm = current->mm; + struct tsb_config *tp; - if (likely(tp->tsb != NULL)) - return; + if (in_atomic() || !mm) { + const struct exception_table_entry *entry; + + entry = search_exception_tables(regs->tpc); + if (entry) { + regs->tpc = entry->fixup; + regs->tnpc = regs->tpc + 4; + return; + } + pr_alert("Unexpected HugeTLB setup in atomic context.\n"); + die_if_kernel("HugeTSB in atomic", regs); + } + + tp = &mm->context.tsb_block[MM_TSB_HUGE]; + if (likely(tp->tsb == NULL)) + tsb_grow(mm, MM_TSB_HUGE, 0); - tsb_grow(mm, MM_TSB_HUGE, 0); tsb_context_switch(mm); smp_tsb_sync(mm); diff --git a/arch/sparc/mm/tlb.c b/arch/sparc/mm/tlb.c index 3e8fec391fe0..ba6ae7ffdc2c 100644 --- a/arch/sparc/mm/tlb.c +++ b/arch/sparc/mm/tlb.c @@ -135,8 +135,15 @@ void set_pmd_at(struct mm_struct *mm, unsigned long addr, mm->context.huge_pte_count++; else mm->context.huge_pte_count--; - if (mm->context.huge_pte_count == 1) - hugetlb_setup(mm); + + /* Do not try to allocate the TSB hash table if we + * don't have one already. We have various locks held + * and thus we'll end up doing a GFP_KERNEL allocation + * in an atomic context. + * + * Instead, we let the first TLB miss on a hugepage + * take care of this. + */ } if (!pmd_none(orig)) { -- GitLab