x86: remove quicklists (985a34bd) · Commits · 戴 / test

quicklists cause a serious memory leak on 32-bit x86, as documented at: http://bugzilla.kernel.org/show_bug.cgi?id=9991 the reason is that the quicklist pool is a special-purpose cache that grows out of proportion. It is not accounted for anywhere and users have no way to even realize that it's the quicklists that are causing RAM usage spikes. It was supposed to be a relatively small pool, but as demonstrated by KOSAKI Motohiro, they can grow as large as: Quicklists: 1194304 kB given how much trouble this code has caused historically, and given that Andrew objected to its introduction on x86 (years ago), the best option at this point is to remove them. [ any performance benefits of caching constructed pgds should be implemented in a more generic way (possibly within the page allocator), while still allowing constructed pages to be allocated by other workloads. ] Signed-off-by:

Thomas Gleixner <tglx@linutronix.de> Signed-off-by:

Ingo Molnar <mingo@elte.hu>

arch/x86/Kconfig

+0 −3

Original line number	Diff line number	Diff line
		@@ -66,9 +66,6 @@ config MMU
		config ZONE_DMA
		def_bool y

		config QUICKLIST
		def_bool X86_32

		config SBUS
		bool

arch/x86/mm/pgtable_32.c

+9 −9

Original line number	Diff line number	Diff line
		@@ -342,12 +342,16 @@ static void pgd_mop_up_pmds(struct mm_struct mm, pgd_t pgdp)

		pgd_t pgd_alloc(struct mm_struct mm)
		{
		pgd_t *pgd = quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
		pgd_t pgd = (pgd_t )__get_free_page(GFP_KERNEL \| __GFP_ZERO);

		mm->pgd = pgd; /* so that alloc_pd can use it */
		/* so that alloc_pd can use it */
		mm->pgd = pgd;
		if (pgd)
		pgd_ctor(pgd);

		if (pgd && !pgd_prepopulate_pmd(mm, pgd)) {
		quicklist_free(0, pgd_dtor, pgd);
		pgd_dtor(pgd);
		free_page((unsigned long)pgd);
		pgd = NULL;
		}

		@@ -357,12 +361,8 @@ pgd_t pgd_alloc(struct mm_struct mm)
		void pgd_free(struct mm_struct mm, pgd_t pgd)
		{
		pgd_mop_up_pmds(mm, pgd);
		quicklist_free(0, pgd_dtor, pgd);
		}

		void check_pgt_cache(void)
		{
		quicklist_trim(0, pgd_dtor, 25, 16);
		pgd_dtor(pgd);
		free_page((unsigned long)pgd);
		}

		void __pte_free_tlb(struct mmu_gather tlb, struct page pte)

include/asm-x86/pgtable_32.h

+2 −3

Original line number	Diff line number	Diff line
		@@ -26,10 +26,9 @@ struct mm_struct;
		struct vm_area_struct;

		extern pgd_t swapper_pg_dir[1024];
		extern struct kmem_cache *pmd_cache;
		void check_pgt_cache(void);

		static inline void pgtable_cache_init(void) { }
		static inline void check_pgt_cache(void) { }
		void paging_init(void);

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