Messages in this thread | | | Subject | Re: [PATCH] mm/vmalloc: Fix regression caused by needless vmalloc_sync_all() | From | Shile Zhang <> | Date | Thu, 14 Nov 2019 08:54:21 +0800 |
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Fix wrong cc list.
On 2019/11/14 05:12, Andrew Morton wrote: > On Wed, 13 Nov 2019 17:55:30 +0800 Shile Zhang <shile.zhang@linux.alibaba.com> wrote: > >> vmalloc_sync_all() was put in the common path in >> __purge_vmap_area_lazy(), for one sync issue only happened on X86_32 >> with PTI enabled. It is needless for X86_64, which caused a big regression >> in UnixBench Shell8 testing on X86_64. >> Similar regression also reported by 0-day kernel test robot in reaim >> benchmarking: >> https://lists.01.org/hyperkitty/list/lkp@lists.01.org/thread/4D3JPPHBNOSPFK2KEPC6KGKS6J25AIDB/ > That is indeed a large performance regression. > >> Fix it by adding more conditions. >> >> Fixes: 3f8fd02b1bf1 ("mm/vmalloc: Sync unmappings in __purge_vmap_area_lazy()") >> >> ... >> >> --- a/mm/vmalloc.c >> +++ b/mm/vmalloc.c >> @@ -1255,11 +1255,17 @@ static bool __purge_vmap_area_lazy(unsigned long start, unsigned long end) >> if (unlikely(valist == NULL)) >> return false; >> >> +#if defined(CONFIG_X86_32) && defined(CONFIG_X86_PAE) > Are we sure that x86_32 is the only architecture whcih is (or ever will > be) affected? > >> /* >> * First make sure the mappings are removed from all page-tables >> * before they are freed. >> + * >> + * This is only needed on x86-32 with !SHARED_KERNEL_PMD, which is >> + * the case on a PAE kernel with PTI enabled. >> */ >> - vmalloc_sync_all(); >> + if (!SHARED_KERNEL_PMD && boot_cpu_has(X86_FEATURE_PTI)) >> + vmalloc_sync_all(); >> +#endif >> >> /* >> * TODO: to calculate a flush range without looping. > CONFIG_X86_PAE depends on CONFIG_X86_32 so no need to check > CONFIG_X86_32?
Yes, Thanks for your review and kindly refactoring!
> From: Andrew Morton <akpm@linux-foundation.org> > Subject: mm-vmalloc-fix-regression-caused-by-needless-vmalloc_sync_all-fix > > simplify config expression, use IS_ENABLED() > > Cc: Dave Hansen <dave.hansen@linux.intel.com> > Cc: Joerg Roedel <jroedel@suse.de> > Cc: Qian Cai <cai@lca.pw> > Cc: Shile Zhang <shile.zhang@linux.alibaba.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > --- > > mm/vmalloc.c | 21 +++++++++++---------- > 1 file changed, 11 insertions(+), 10 deletions(-) > > --- a/mm/vmalloc.c~mm-vmalloc-fix-regression-caused-by-needless-vmalloc_sync_all-fix > +++ a/mm/vmalloc.c > @@ -1255,16 +1255,17 @@ static bool __purge_vmap_area_lazy(unsig > if (unlikely(valist == NULL)) > return false; > > -#if defined(CONFIG_X86_32) && defined(CONFIG_X86_PAE) > - /* > - * First make sure the mappings are removed from all page-tables > - * before they are freed. > - * > - * This is only needed on x86-32 with !SHARED_KERNEL_PMD, which is > - * the case on a PAE kernel with PTI enabled. > - */ > - if (!SHARED_KERNEL_PMD && boot_cpu_has(X86_FEATURE_PTI)) > - vmalloc_sync_all(); > + if (IS_ENABLED(CONFIG_X86_PAE)) { > + /* > + * First make sure the mappings are removed from all page-tables > + * before they are freed. > + * > + * This is only needed on x86-32 with !SHARED_KERNEL_PMD, which > + * is the case on a PAE kernel with PTI enabled. > + */ > + if (!SHARED_KERNEL_PMD && boot_cpu_has(X86_FEATURE_PTI)) > + vmalloc_sync_all(); > + } > #endif > > /* > _
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