x86: remove quicklists

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>

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f41c9538ca303f2fdb5b231cc9c9592b72024e23..237fc128143d43fbe3c232de29cb47ffec331d90 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -66,9 +66,6 @@ config MMU
 config ZONE_DMA
        def_bool y
 
-config QUICKLIST
-       def_bool X86_32
-
 config SBUS
        bool
 

diff --git a/arch/x86/mm/pgtable_32.c b/arch/x86/mm/pgtable_32.c
index 73aba7125203764b41a3cb3af48ac6d5d5cee5a4..2f9e9afcb9f4270d6e5f5a496f33999d6ce8298b 100644 (file)
--- a/arch/x86/mm/pgtable_32.c
+++ b/arch/x86/mm/pgtable_32.c
@@ -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)

diff --git a/include/asm-x86/pgtable_32.h b/include/asm-x86/pgtable_32.h
index a842c7222b1eef0f598a8de4a4c5375506e0b2c5..4e6a0fca0b47c1fc1941ef368618c3ef691ddfcb 100644 (file)
--- a/include/asm-x86/pgtable_32.h
+++ b/include/asm-x86/pgtable_32.h
@@ -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 pgtable_cache_init(void) { }
+static inline void check_pgt_cache(void) { }
 void paging_init(void);