| Message ID | 20181210142105.6750-1-rafael.tinoco@linaro.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | mm/zsmalloc.c: Fix zsmalloc 32-bit PAE support | expand |
On 10/12/2018 14:21, Rafael David Tinoco wrote: > On 32-bit systems, zsmalloc uses HIGHMEM and, when PAE is enabled, the > physical frame number might be so big that zsmalloc obj encoding (to > location) will break, causing: > > BUG: KASAN: null-ptr-deref in zs_map_object+0xa4/0x2bc > Read of size 4 at addr 00000000 by task mkfs.ext4/623 > CPU: 2 PID: 623 Comm: mkfs.ext4 Not tainted 4.19.0-rc8-00017-g8239bc6d3307-dirty #15 > Hardware name: Generic DT based system > [<c0418f7c>] (unwind_backtrace) from [<c0410ca4>] (show_stack+0x20/0x24) > [<c0410ca4>] (show_stack) from [<c16bd540>] (dump_stack+0xbc/0xe8) > [<c16bd540>] (dump_stack) from [<c06cab74>] (kasan_report+0x248/0x390) > [<c06cab74>] (kasan_report) from [<c06c94e8>] (__asan_load4+0x78/0xb4) > [<c06c94e8>] (__asan_load4) from [<c06ddc24>] (zs_map_object+0xa4/0x2bc) > [<c06ddc24>] (zs_map_object) from [<bf0bbbd8>] (zram_bvec_rw.constprop.2+0x324/0x8e4 [zram]) > [<bf0bbbd8>] (zram_bvec_rw.constprop.2 [zram]) from [<bf0bc3cc>] (zram_make_request+0x234/0x46c [zram]) > [<bf0bc3cc>] (zram_make_request [zram]) from [<c09aff9c>] (generic_make_request+0x304/0x63c) > [<c09aff9c>] (generic_make_request) from [<c09b0320>] (submit_bio+0x4c/0x1c8) > [<c09b0320>] (submit_bio) from [<c0743570>] (submit_bh_wbc.constprop.15+0x238/0x26c) > [<c0743570>] (submit_bh_wbc.constprop.15) from [<c0746cf8>] (__block_write_full_page+0x524/0x76c) > [<c0746cf8>] (__block_write_full_page) from [<c07472c4>] (block_write_full_page+0x1bc/0x1d4) > [<c07472c4>] (block_write_full_page) from [<c0748eb4>] (blkdev_writepage+0x24/0x28) > [<c0748eb4>] (blkdev_writepage) from [<c064a780>] (__writepage+0x44/0x78) > [<c064a780>] (__writepage) from [<c064b50c>] (write_cache_pages+0x3b8/0x800) > [<c064b50c>] (write_cache_pages) from [<c064dd78>] (generic_writepages+0x74/0xa0) > [<c064dd78>] (generic_writepages) from [<c0748e64>] (blkdev_writepages+0x18/0x1c) > [<c0748e64>] (blkdev_writepages) from [<c064e890>] (do_writepages+0x68/0x134) > [<c064e890>] (do_writepages) from [<c06368a4>] (__filemap_fdatawrite_range+0xb0/0xf4) > [<c06368a4>] (__filemap_fdatawrite_range) from [<c0636b68>] (file_write_and_wait_range+0x64/0xd0) > [<c0636b68>] (file_write_and_wait_range) from [<c0747af8>] (blkdev_fsync+0x54/0x84) > [<c0747af8>] (blkdev_fsync) from [<c0739dac>] (vfs_fsync_range+0x70/0xd4) > [<c0739dac>] (vfs_fsync_range) from [<c0739e98>] (do_fsync+0x4c/0x80) > [<c0739e98>] (do_fsync) from [<c073a26c>] (sys_fsync+0x1c/0x20) > [<c073a26c>] (sys_fsync) from [<c0401000>] (ret_fast_syscall+0x0/0x2c) > > when trying to decode (the pfn) and map the object. > > That happens because one architecture might not re-define > MAX_PHYSMEM_BITS, like in this ARM 32-bit w/ LPAE enabled example. For > 32-bit systems, if not re-defined, MAX_POSSIBLE_PHYSMEM_BITS will > default to BITS_PER_LONG (32) in most cases, and, with PAE enabled, > _PFN_BITS might be wrong: which may cause obj variable to overflow if > frame number is in HIGHMEM and referencing a page above the 4GB > watermark. > > commit 6e00ec00b1a7 ("staging: zsmalloc: calculate MAX_PHYSMEM_BITS if > not defined") realized MAX_PHYSMEM_BITS depended on SPARSEMEM headers > and "fixed" it by calculating it using BITS_PER_LONG if SPARSEMEM wasn't > used, like in the example given above. > > Systems with potential for PAE exist for a long time and assuming > BITS_PER_LONG seems inadequate. Defining MAX_PHYSMEM_BITS looks better, > however it is NOT a constant anymore for x86. > > SO, instead, MAX_POSSIBLE_PHYSMEM_BITS should be defined by every > architecture using zsmalloc, together with a sanity check for > MAX_POSSIBLE_PHYSMEM_BITS being too big on 32-bit systems. > > Link: https://bugs.linaro.org/show_bug.cgi?id=3765#c17 > Signed-off-by: Rafael David Tinoco <rafael.tinoco@linaro.org> > --- > arch/arm/include/asm/pgtable-2level-types.h | 2 ++ > arch/arm/include/asm/pgtable-3level-types.h | 2 ++ > arch/arm64/include/asm/pgtable-types.h | 2 ++ > arch/ia64/include/asm/page.h | 2 ++ > arch/mips/include/asm/page.h | 2 ++ > arch/powerpc/include/asm/mmu.h | 2 ++ > arch/s390/include/asm/page.h | 2 ++ > arch/sh/include/asm/page.h | 2 ++ > arch/sparc/include/asm/page_32.h | 2 ++ > arch/sparc/include/asm/page_64.h | 2 ++ > arch/x86/include/asm/pgtable-2level_types.h | 2 ++ > arch/x86/include/asm/pgtable-3level_types.h | 3 +- > arch/x86/include/asm/pgtable_64_types.h | 4 +-- > mm/zsmalloc.c | 35 +++++++++++---------- > 14 files changed, 45 insertions(+), 19 deletions(-) > > diff --git a/arch/arm/include/asm/pgtable-2level-types.h b/arch/arm/include/asm/pgtable-2level-types.h > index 66cb5b0e89c5..552dba411324 100644 > --- a/arch/arm/include/asm/pgtable-2level-types.h > +++ b/arch/arm/include/asm/pgtable-2level-types.h > @@ -64,4 +64,6 @@ typedef pteval_t pgprot_t; > > #endif /* STRICT_MM_TYPECHECKS */ > > +#define MAX_POSSIBLE_PHYSMEM_BITS 32 > + > #endif /* _ASM_PGTABLE_2LEVEL_TYPES_H */ > diff --git a/arch/arm/include/asm/pgtable-3level-types.h b/arch/arm/include/asm/pgtable-3level-types.h > index 921aa30259c4..664c39e6517c 100644 > --- a/arch/arm/include/asm/pgtable-3level-types.h > +++ b/arch/arm/include/asm/pgtable-3level-types.h > @@ -67,4 +67,6 @@ typedef pteval_t pgprot_t; > > #endif /* STRICT_MM_TYPECHECKS */ > > +#define MAX_POSSIBLE_PHYSMEM_BITS 36 Nit: with LPAE, physical addresses go up to 40 bits, not just 36. Robin. > + > #endif /* _ASM_PGTABLE_3LEVEL_TYPES_H */ > diff --git a/arch/arm64/include/asm/pgtable-types.h b/arch/arm64/include/asm/pgtable-types.h > index 345a072b5856..45c3834eb4c8 100644 > --- a/arch/arm64/include/asm/pgtable-types.h > +++ b/arch/arm64/include/asm/pgtable-types.h > @@ -64,4 +64,6 @@ typedef struct { pteval_t pgprot; } pgprot_t; > #include <asm-generic/5level-fixup.h> > #endif > > +#define MAX_POSSIBLE_PHYSMEM_BITS CONFIG_ARM64_PA_BITS > + > #endif /* __ASM_PGTABLE_TYPES_H */ > diff --git a/arch/ia64/include/asm/page.h b/arch/ia64/include/asm/page.h > index 5798bd2b462c..a3e055979e46 100644 > --- a/arch/ia64/include/asm/page.h > +++ b/arch/ia64/include/asm/page.h > @@ -235,4 +235,6 @@ get_order (unsigned long size) > > #define __HAVE_ARCH_GATE_AREA 1 > > +#define MAX_POSSIBLE_PHYSMEM_BITS 50 > + > #endif /* _ASM_IA64_PAGE_H */ > diff --git a/arch/mips/include/asm/page.h b/arch/mips/include/asm/page.h > index e8cc328fce2d..f6a5dea1a66c 100644 > --- a/arch/mips/include/asm/page.h > +++ b/arch/mips/include/asm/page.h > @@ -263,4 +263,6 @@ extern int __virt_addr_valid(const volatile void *kaddr); > #include <asm-generic/memory_model.h> > #include <asm-generic/getorder.h> > > +#define MAX_POSSIBLE_PHYSMEM_BITS 48 > + > #endif /* _ASM_PAGE_H */ > diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h > index eb20eb3b8fb0..2ebc1d2d9a5c 100644 > --- a/arch/powerpc/include/asm/mmu.h > +++ b/arch/powerpc/include/asm/mmu.h > @@ -324,6 +324,8 @@ static inline u16 get_mm_addr_key(struct mm_struct *mm, unsigned long address) > #define MAX_PHYSMEM_BITS 46 > #endif > > +#define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS > + > #ifdef CONFIG_PPC_BOOK3S_64 > #include <asm/book3s/64/mmu.h> > #else /* CONFIG_PPC_BOOK3S_64 */ > diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h > index a4d38092530a..8abec1461bf7 100644 > --- a/arch/s390/include/asm/page.h > +++ b/arch/s390/include/asm/page.h > @@ -180,4 +180,6 @@ static inline int devmem_is_allowed(unsigned long pfn) > #include <asm-generic/memory_model.h> > #include <asm-generic/getorder.h> > > +#define MAX_POSSIBLE_PHYSMEM_BITS CONFIG_MAX_PHYSMEM_BITS > + > #endif /* _S390_PAGE_H */ > diff --git a/arch/sh/include/asm/page.h b/arch/sh/include/asm/page.h > index 5eef8be3e59f..40c7e12cf09e 100644 > --- a/arch/sh/include/asm/page.h > +++ b/arch/sh/include/asm/page.h > @@ -205,4 +205,6 @@ typedef struct page *pgtable_t; > #define ARCH_SLAB_MINALIGN 8 > #endif > > +#define MAX_POSSIBLE_PHYSMEM_BITS 32 > + > #endif /* __ASM_SH_PAGE_H */ > diff --git a/arch/sparc/include/asm/page_32.h b/arch/sparc/include/asm/page_32.h > index b76d59edec8c..14e9ca4659d7 100644 > --- a/arch/sparc/include/asm/page_32.h > +++ b/arch/sparc/include/asm/page_32.h > @@ -139,4 +139,6 @@ extern unsigned long pfn_base; > #include <asm-generic/memory_model.h> > #include <asm-generic/getorder.h> > > +#define MAX_POSSIBLE_PHYSMEM_BITS 32 > + > #endif /* _SPARC_PAGE_H */ > diff --git a/arch/sparc/include/asm/page_64.h b/arch/sparc/include/asm/page_64.h > index e80f2d5bf62f..6d6f3654ead1 100644 > --- a/arch/sparc/include/asm/page_64.h > +++ b/arch/sparc/include/asm/page_64.h > @@ -163,4 +163,6 @@ extern unsigned long PAGE_OFFSET; > > #include <asm-generic/getorder.h> > > +#define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYS_ADDRESS_BITS > + > #endif /* _SPARC64_PAGE_H */ > diff --git a/arch/x86/include/asm/pgtable-2level_types.h b/arch/x86/include/asm/pgtable-2level_types.h > index 6deb6cd236e3..c2eae59e6505 100644 > --- a/arch/x86/include/asm/pgtable-2level_types.h > +++ b/arch/x86/include/asm/pgtable-2level_types.h > @@ -38,4 +38,6 @@ typedef union { > /* This covers all VMSPLIT_* and VMSPLIT_*_OPT variants */ > #define PGD_KERNEL_START (CONFIG_PAGE_OFFSET >> PGDIR_SHIFT) > > +#define MAX_POSSIBLE_PHYSMEM_BITS 32 > + > #endif /* _ASM_X86_PGTABLE_2LEVEL_DEFS_H */ > diff --git a/arch/x86/include/asm/pgtable-3level_types.h b/arch/x86/include/asm/pgtable-3level_types.h > index 33845d36897c..5fce514a49a0 100644 > --- a/arch/x86/include/asm/pgtable-3level_types.h > +++ b/arch/x86/include/asm/pgtable-3level_types.h > @@ -45,7 +45,8 @@ typedef union { > */ > #define PTRS_PER_PTE 512 > > -#define MAX_POSSIBLE_PHYSMEM_BITS 36 > #define PGD_KERNEL_START (CONFIG_PAGE_OFFSET >> PGDIR_SHIFT) > > +#define MAX_POSSIBLE_PHYSMEM_BITS 36 > + > #endif /* _ASM_X86_PGTABLE_3LEVEL_DEFS_H */ > diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h > index 84bd9bdc1987..d808cfde3d19 100644 > --- a/arch/x86/include/asm/pgtable_64_types.h > +++ b/arch/x86/include/asm/pgtable_64_types.h > @@ -64,8 +64,6 @@ extern unsigned int ptrs_per_p4d; > #define P4D_SIZE (_AC(1, UL) << P4D_SHIFT) > #define P4D_MASK (~(P4D_SIZE - 1)) > > -#define MAX_POSSIBLE_PHYSMEM_BITS 52 > - > #else /* CONFIG_X86_5LEVEL */ > > /* > @@ -154,4 +152,6 @@ extern unsigned int ptrs_per_p4d; > > #define PGD_KERNEL_START ((PAGE_SIZE / 2) / sizeof(pgd_t)) > > +#define MAX_POSSIBLE_PHYSMEM_BITS (pgtable_l5_enabled() ? 52 : 46) > + > #endif /* _ASM_X86_PGTABLE_64_DEFS_H */ > diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c > index 0787d33b80d8..132c20b6fd4f 100644 > --- a/mm/zsmalloc.c > +++ b/mm/zsmalloc.c > @@ -80,23 +80,7 @@ > * as single (unsigned long) handle value. > * > * Note that object index <obj_idx> starts from 0. > - * > - * This is made more complicated by various memory models and PAE. > - */ > - > -#ifndef MAX_POSSIBLE_PHYSMEM_BITS > -#ifdef MAX_PHYSMEM_BITS > -#define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS > -#else > -/* > - * If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just > - * be PAGE_SHIFT > */ > -#define MAX_POSSIBLE_PHYSMEM_BITS BITS_PER_LONG > -#endif > -#endif > - > -#define _PFN_BITS (MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT) > > /* > * Memory for allocating for handle keeps object position by > @@ -116,6 +100,25 @@ > */ > #define OBJ_ALLOCATED_TAG 1 > #define OBJ_TAG_BITS 1 > + > +/* > + * MAX_POSSIBLE_PHYSMEM_BITS should be defined by all archs using zsmalloc: > + * Trying to guess it from MAX_PHYSMEM_BITS, or considering it BITS_PER_LONG, > + * proved to be wrong by not considering PAE capabilities, or using SPARSEMEM > + * only headers, leading to bad object encoding due to object index overflow. > + */ > +#ifndef MAX_POSSIBLE_PHYSMEM_BITS > + #define MAX_POSSIBLE_PHYSMEM_BITS BITS_PER_LONG > + #error "MAX_POSSIBLE_PHYSMEM_BITS HAS to be defined by arch using zsmalloc"; > +#else > + #ifndef CONFIG_64BIT > + #if (MAX_POSSIBLE_PHYSMEM_BITS >= (BITS_PER_LONG + PAGE_SHIFT - OBJ_TAG_BITS)) > + #error "MAX_POSSIBLE_PHYSMEM_BITS is wrong for this arch"; > + #endif > + #endif > +#endif > + > +#define _PFN_BITS (MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT) > #define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS) > #define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1) > >
On Mon, Dec 10, 2018 at 02:35:55PM +0000, Robin Murphy wrote: > On 10/12/2018 14:21, Rafael David Tinoco wrote: > >On 32-bit systems, zsmalloc uses HIGHMEM and, when PAE is enabled, the > >physical frame number might be so big that zsmalloc obj encoding (to > >location) will break, causing: > > > >BUG: KASAN: null-ptr-deref in zs_map_object+0xa4/0x2bc > >Read of size 4 at addr 00000000 by task mkfs.ext4/623 > >CPU: 2 PID: 623 Comm: mkfs.ext4 Not tainted 4.19.0-rc8-00017-g8239bc6d3307-dirty #15 > >Hardware name: Generic DT based system > >[<c0418f7c>] (unwind_backtrace) from [<c0410ca4>] (show_stack+0x20/0x24) > >[<c0410ca4>] (show_stack) from [<c16bd540>] (dump_stack+0xbc/0xe8) > >[<c16bd540>] (dump_stack) from [<c06cab74>] (kasan_report+0x248/0x390) > >[<c06cab74>] (kasan_report) from [<c06c94e8>] (__asan_load4+0x78/0xb4) > >[<c06c94e8>] (__asan_load4) from [<c06ddc24>] (zs_map_object+0xa4/0x2bc) > >[<c06ddc24>] (zs_map_object) from [<bf0bbbd8>] (zram_bvec_rw.constprop.2+0x324/0x8e4 [zram]) > >[<bf0bbbd8>] (zram_bvec_rw.constprop.2 [zram]) from [<bf0bc3cc>] (zram_make_request+0x234/0x46c [zram]) > >[<bf0bc3cc>] (zram_make_request [zram]) from [<c09aff9c>] (generic_make_request+0x304/0x63c) > >[<c09aff9c>] (generic_make_request) from [<c09b0320>] (submit_bio+0x4c/0x1c8) > >[<c09b0320>] (submit_bio) from [<c0743570>] (submit_bh_wbc.constprop.15+0x238/0x26c) > >[<c0743570>] (submit_bh_wbc.constprop.15) from [<c0746cf8>] (__block_write_full_page+0x524/0x76c) > >[<c0746cf8>] (__block_write_full_page) from [<c07472c4>] (block_write_full_page+0x1bc/0x1d4) > >[<c07472c4>] (block_write_full_page) from [<c0748eb4>] (blkdev_writepage+0x24/0x28) > >[<c0748eb4>] (blkdev_writepage) from [<c064a780>] (__writepage+0x44/0x78) > >[<c064a780>] (__writepage) from [<c064b50c>] (write_cache_pages+0x3b8/0x800) > >[<c064b50c>] (write_cache_pages) from [<c064dd78>] (generic_writepages+0x74/0xa0) > >[<c064dd78>] (generic_writepages) from [<c0748e64>] (blkdev_writepages+0x18/0x1c) > >[<c0748e64>] (blkdev_writepages) from [<c064e890>] (do_writepages+0x68/0x134) > >[<c064e890>] (do_writepages) from [<c06368a4>] (__filemap_fdatawrite_range+0xb0/0xf4) > >[<c06368a4>] (__filemap_fdatawrite_range) from [<c0636b68>] (file_write_and_wait_range+0x64/0xd0) > >[<c0636b68>] (file_write_and_wait_range) from [<c0747af8>] (blkdev_fsync+0x54/0x84) > >[<c0747af8>] (blkdev_fsync) from [<c0739dac>] (vfs_fsync_range+0x70/0xd4) > >[<c0739dac>] (vfs_fsync_range) from [<c0739e98>] (do_fsync+0x4c/0x80) > >[<c0739e98>] (do_fsync) from [<c073a26c>] (sys_fsync+0x1c/0x20) > >[<c073a26c>] (sys_fsync) from [<c0401000>] (ret_fast_syscall+0x0/0x2c) > > > >when trying to decode (the pfn) and map the object. > > > >That happens because one architecture might not re-define > >MAX_PHYSMEM_BITS, like in this ARM 32-bit w/ LPAE enabled example. For > >32-bit systems, if not re-defined, MAX_POSSIBLE_PHYSMEM_BITS will > >default to BITS_PER_LONG (32) in most cases, and, with PAE enabled, > >_PFN_BITS might be wrong: which may cause obj variable to overflow if > >frame number is in HIGHMEM and referencing a page above the 4GB > >watermark. > > > >commit 6e00ec00b1a7 ("staging: zsmalloc: calculate MAX_PHYSMEM_BITS if > >not defined") realized MAX_PHYSMEM_BITS depended on SPARSEMEM headers > >and "fixed" it by calculating it using BITS_PER_LONG if SPARSEMEM wasn't > >used, like in the example given above. > > > >Systems with potential for PAE exist for a long time and assuming > >BITS_PER_LONG seems inadequate. Defining MAX_PHYSMEM_BITS looks better, > >however it is NOT a constant anymore for x86. > > > >SO, instead, MAX_POSSIBLE_PHYSMEM_BITS should be defined by every > >architecture using zsmalloc, together with a sanity check for > >MAX_POSSIBLE_PHYSMEM_BITS being too big on 32-bit systems. > > > >Link: https://bugs.linaro.org/show_bug.cgi?id=3765#c17 > >Signed-off-by: Rafael David Tinoco <rafael.tinoco@linaro.org> > >--- > > arch/arm/include/asm/pgtable-2level-types.h | 2 ++ > > arch/arm/include/asm/pgtable-3level-types.h | 2 ++ > > arch/arm64/include/asm/pgtable-types.h | 2 ++ > > arch/ia64/include/asm/page.h | 2 ++ > > arch/mips/include/asm/page.h | 2 ++ > > arch/powerpc/include/asm/mmu.h | 2 ++ > > arch/s390/include/asm/page.h | 2 ++ > > arch/sh/include/asm/page.h | 2 ++ > > arch/sparc/include/asm/page_32.h | 2 ++ > > arch/sparc/include/asm/page_64.h | 2 ++ > > arch/x86/include/asm/pgtable-2level_types.h | 2 ++ > > arch/x86/include/asm/pgtable-3level_types.h | 3 +- > > arch/x86/include/asm/pgtable_64_types.h | 4 +-- > > mm/zsmalloc.c | 35 +++++++++++---------- > > 14 files changed, 45 insertions(+), 19 deletions(-) > > > >diff --git a/arch/arm/include/asm/pgtable-2level-types.h b/arch/arm/include/asm/pgtable-2level-types.h > >index 66cb5b0e89c5..552dba411324 100644 > >--- a/arch/arm/include/asm/pgtable-2level-types.h > >+++ b/arch/arm/include/asm/pgtable-2level-types.h > >@@ -64,4 +64,6 @@ typedef pteval_t pgprot_t; > > #endif /* STRICT_MM_TYPECHECKS */ > >+#define MAX_POSSIBLE_PHYSMEM_BITS 32 > >+ > > #endif /* _ASM_PGTABLE_2LEVEL_TYPES_H */ > >diff --git a/arch/arm/include/asm/pgtable-3level-types.h b/arch/arm/include/asm/pgtable-3level-types.h > >index 921aa30259c4..664c39e6517c 100644 > >--- a/arch/arm/include/asm/pgtable-3level-types.h > >+++ b/arch/arm/include/asm/pgtable-3level-types.h > >@@ -67,4 +67,6 @@ typedef pteval_t pgprot_t; > > #endif /* STRICT_MM_TYPECHECKS */ > >+#define MAX_POSSIBLE_PHYSMEM_BITS 36 > > Nit: with LPAE, physical addresses go up to 40 bits, not just 36. Right, with that set at 40, we get: #define _PFN_BITS (MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT) == 28 #define OBJ_TAG_BITS 1 #define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS) == 3 #define ZS_MAX_ZSPAGE_ORDER 2 #define ZS_MAX_PAGES_PER_ZSPAGE (_AC(1, UL) << ZS_MAX_ZSPAGE_ORDER) == 4 #define ZS_MIN_ALLOC_SIZE \ MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS)) == 4 << 12 >> 3 = 2048 or half-page allocations. Given this in Documentation/vm/zsmalloc.rst: On the other hand, if we just use single (0-order) pages, it would suffer from very high fragmentation -- any object of size PAGE_SIZE/2 or larger would occupy an entire page. This was one of the major issues with its predecessor (xvmalloc). It seems that would not be acceptable, so I have to ask whether using an unsigned long to store PFN + object ID is really acceptable. Maybe the real solution to this problem is to stop using an unsigned long to contain both the PFN and object ID?
On Mon, Dec 10, 2018 at 12:21:05PM -0200, Rafael David Tinoco wrote: > diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h > index 84bd9bdc1987..d808cfde3d19 100644 > --- a/arch/x86/include/asm/pgtable_64_types.h > +++ b/arch/x86/include/asm/pgtable_64_types.h > @@ -64,8 +64,6 @@ extern unsigned int ptrs_per_p4d; > #define P4D_SIZE (_AC(1, UL) << P4D_SHIFT) > #define P4D_MASK (~(P4D_SIZE - 1)) > > -#define MAX_POSSIBLE_PHYSMEM_BITS 52 > - > #else /* CONFIG_X86_5LEVEL */ > > /* > @@ -154,4 +152,6 @@ extern unsigned int ptrs_per_p4d; > > #define PGD_KERNEL_START ((PAGE_SIZE / 2) / sizeof(pgd_t)) > > +#define MAX_POSSIBLE_PHYSMEM_BITS (pgtable_l5_enabled() ? 52 : 46) > + ... > #endif /* _ASM_X86_PGTABLE_64_DEFS_H */ > diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c > index 0787d33b80d8..132c20b6fd4f 100644 > --- a/mm/zsmalloc.c > +++ b/mm/zsmalloc.c ... > @@ -116,6 +100,25 @@ > */ > #define OBJ_ALLOCATED_TAG 1 > #define OBJ_TAG_BITS 1 > + > +/* > + * MAX_POSSIBLE_PHYSMEM_BITS should be defined by all archs using zsmalloc: > + * Trying to guess it from MAX_PHYSMEM_BITS, or considering it BITS_PER_LONG, > + * proved to be wrong by not considering PAE capabilities, or using SPARSEMEM > + * only headers, leading to bad object encoding due to object index overflow. > + */ > +#ifndef MAX_POSSIBLE_PHYSMEM_BITS > + #define MAX_POSSIBLE_PHYSMEM_BITS BITS_PER_LONG > + #error "MAX_POSSIBLE_PHYSMEM_BITS HAS to be defined by arch using zsmalloc"; > +#else > + #ifndef CONFIG_64BIT > + #if (MAX_POSSIBLE_PHYSMEM_BITS >= (BITS_PER_LONG + PAGE_SHIFT - OBJ_TAG_BITS)) > + #error "MAX_POSSIBLE_PHYSMEM_BITS is wrong for this arch"; > + #endif > + #endif > +#endif > + > +#define _PFN_BITS (MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT) > #define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS) > #define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1) Have you tested it with CONFIG_X86_5LEVEL=y? ASAICS, the patch makes OBJ_INDEX_BITS and what depends from it dynamic -- it depends what paging mode we are booting in. ZS_SIZE_CLASSES depends indirectly on OBJ_INDEX_BITS and I don't see how struct zs_pool definition can compile with dynamic ZS_SIZE_CLASSES. Hm?
On 12/10/18 1:15 PM, Kirill A. Shutemov wrote: > On Mon, Dec 10, 2018 at 12:21:05PM -0200, Rafael David Tinoco wrote: >> diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h >> index 84bd9bdc1987..d808cfde3d19 100644 >> --- a/arch/x86/include/asm/pgtable_64_types.h >> +++ b/arch/x86/include/asm/pgtable_64_types.h >> @@ -64,8 +64,6 @@ extern unsigned int ptrs_per_p4d; >> #define P4D_SIZE (_AC(1, UL) << P4D_SHIFT) >> #define P4D_MASK (~(P4D_SIZE - 1)) >> >> -#define MAX_POSSIBLE_PHYSMEM_BITS 52 >> - >> #else /* CONFIG_X86_5LEVEL */ >> >> /* >> @@ -154,4 +152,6 @@ extern unsigned int ptrs_per_p4d; >> >> #define PGD_KERNEL_START ((PAGE_SIZE / 2) / sizeof(pgd_t)) >> >> +#define MAX_POSSIBLE_PHYSMEM_BITS (pgtable_l5_enabled() ? 52 : 46) >> + > > ... > >> #endif /* _ASM_X86_PGTABLE_64_DEFS_H */ >> diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c >> index 0787d33b80d8..132c20b6fd4f 100644 >> --- a/mm/zsmalloc.c >> +++ b/mm/zsmalloc.c > > ... > >> @@ -116,6 +100,25 @@ >> */ >> #define OBJ_ALLOCATED_TAG 1 >> #define OBJ_TAG_BITS 1 >> + >> +/* >> + * MAX_POSSIBLE_PHYSMEM_BITS should be defined by all archs using zsmalloc: >> + * Trying to guess it from MAX_PHYSMEM_BITS, or considering it BITS_PER_LONG, >> + * proved to be wrong by not considering PAE capabilities, or using SPARSEMEM >> + * only headers, leading to bad object encoding due to object index overflow. >> + */ >> +#ifndef MAX_POSSIBLE_PHYSMEM_BITS >> + #define MAX_POSSIBLE_PHYSMEM_BITS BITS_PER_LONG >> + #error "MAX_POSSIBLE_PHYSMEM_BITS HAS to be defined by arch using zsmalloc"; >> +#else >> + #ifndef CONFIG_64BIT >> + #if (MAX_POSSIBLE_PHYSMEM_BITS >= (BITS_PER_LONG + PAGE_SHIFT - OBJ_TAG_BITS)) >> + #error "MAX_POSSIBLE_PHYSMEM_BITS is wrong for this arch"; >> + #endif >> + #endif >> +#endif >> + >> +#define _PFN_BITS (MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT) >> #define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS) >> #define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1) > > Have you tested it with CONFIG_X86_5LEVEL=y? > > ASAICS, the patch makes OBJ_INDEX_BITS and what depends from it dynamic -- > it depends what paging mode we are booting in. ZS_SIZE_CLASSES depends > indirectly on OBJ_INDEX_BITS and I don't see how struct zs_pool definition > can compile with dynamic ZS_SIZE_CLASSES. > > Hm? > You're right, terribly sorry. This was a last time change. mm/zsmalloc.c:256:21: error: variably modified ‘size_class’ at file scope I'll revisit the patch. Any other comments are welcome. Thank you
On 12/10/18 1:05 PM, Russell King - ARM Linux wrote: > On Mon, Dec 10, 2018 at 02:35:55PM +0000, Robin Murphy wrote: >> On 10/12/2018 14:21, Rafael David Tinoco wrote: >>> On 32-bit systems, zsmalloc uses HIGHMEM and, when PAE is enabled, the >>> physical frame number might be so big that zsmalloc obj encoding (to >>> location) will break, causing: >>> >>> BUG: KASAN: null-ptr-deref in zs_map_object+0xa4/0x2bc >>> Read of size 4 at addr 00000000 by task mkfs.ext4/623 >>> CPU: 2 PID: 623 Comm: mkfs.ext4 Not tainted 4.19.0-rc8-00017-g8239bc6d3307-dirty #15 >>> Hardware name: Generic DT based system >>> [<c0418f7c>] (unwind_backtrace) from [<c0410ca4>] (show_stack+0x20/0x24) >>> [<c0410ca4>] (show_stack) from [<c16bd540>] (dump_stack+0xbc/0xe8) >>> [<c16bd540>] (dump_stack) from [<c06cab74>] (kasan_report+0x248/0x390) >>> [<c06cab74>] (kasan_report) from [<c06c94e8>] (__asan_load4+0x78/0xb4) >>> [<c06c94e8>] (__asan_load4) from [<c06ddc24>] (zs_map_object+0xa4/0x2bc) >>> [<c06ddc24>] (zs_map_object) from [<bf0bbbd8>] (zram_bvec_rw.constprop.2+0x324/0x8e4 [zram]) >>> [<bf0bbbd8>] (zram_bvec_rw.constprop.2 [zram]) from [<bf0bc3cc>] (zram_make_request+0x234/0x46c [zram]) >>> [<bf0bc3cc>] (zram_make_request [zram]) from [<c09aff9c>] (generic_make_request+0x304/0x63c) >>> [<c09aff9c>] (generic_make_request) from [<c09b0320>] (submit_bio+0x4c/0x1c8) >>> [<c09b0320>] (submit_bio) from [<c0743570>] (submit_bh_wbc.constprop.15+0x238/0x26c) >>> [<c0743570>] (submit_bh_wbc.constprop.15) from [<c0746cf8>] (__block_write_full_page+0x524/0x76c) >>> [<c0746cf8>] (__block_write_full_page) from [<c07472c4>] (block_write_full_page+0x1bc/0x1d4) >>> [<c07472c4>] (block_write_full_page) from [<c0748eb4>] (blkdev_writepage+0x24/0x28) >>> [<c0748eb4>] (blkdev_writepage) from [<c064a780>] (__writepage+0x44/0x78) >>> [<c064a780>] (__writepage) from [<c064b50c>] (write_cache_pages+0x3b8/0x800) >>> [<c064b50c>] (write_cache_pages) from [<c064dd78>] (generic_writepages+0x74/0xa0) >>> [<c064dd78>] (generic_writepages) from [<c0748e64>] (blkdev_writepages+0x18/0x1c) >>> [<c0748e64>] (blkdev_writepages) from [<c064e890>] (do_writepages+0x68/0x134) >>> [<c064e890>] (do_writepages) from [<c06368a4>] (__filemap_fdatawrite_range+0xb0/0xf4) >>> [<c06368a4>] (__filemap_fdatawrite_range) from [<c0636b68>] (file_write_and_wait_range+0x64/0xd0) >>> [<c0636b68>] (file_write_and_wait_range) from [<c0747af8>] (blkdev_fsync+0x54/0x84) >>> [<c0747af8>] (blkdev_fsync) from [<c0739dac>] (vfs_fsync_range+0x70/0xd4) >>> [<c0739dac>] (vfs_fsync_range) from [<c0739e98>] (do_fsync+0x4c/0x80) >>> [<c0739e98>] (do_fsync) from [<c073a26c>] (sys_fsync+0x1c/0x20) >>> [<c073a26c>] (sys_fsync) from [<c0401000>] (ret_fast_syscall+0x0/0x2c) >>> >>> when trying to decode (the pfn) and map the object. >>> >>> That happens because one architecture might not re-define >>> MAX_PHYSMEM_BITS, like in this ARM 32-bit w/ LPAE enabled example. For >>> 32-bit systems, if not re-defined, MAX_POSSIBLE_PHYSMEM_BITS will >>> default to BITS_PER_LONG (32) in most cases, and, with PAE enabled, >>> _PFN_BITS might be wrong: which may cause obj variable to overflow if >>> frame number is in HIGHMEM and referencing a page above the 4GB >>> watermark. >>> >>> commit 6e00ec00b1a7 ("staging: zsmalloc: calculate MAX_PHYSMEM_BITS if >>> not defined") realized MAX_PHYSMEM_BITS depended on SPARSEMEM headers >>> and "fixed" it by calculating it using BITS_PER_LONG if SPARSEMEM wasn't >>> used, like in the example given above. >>> >>> Systems with potential for PAE exist for a long time and assuming >>> BITS_PER_LONG seems inadequate. Defining MAX_PHYSMEM_BITS looks better, >>> however it is NOT a constant anymore for x86. >>> >>> SO, instead, MAX_POSSIBLE_PHYSMEM_BITS should be defined by every >>> architecture using zsmalloc, together with a sanity check for >>> MAX_POSSIBLE_PHYSMEM_BITS being too big on 32-bit systems. >>> >>> Link: https://bugs.linaro.org/show_bug.cgi?id=3765#c17 >>> Signed-off-by: Rafael David Tinoco <rafael.tinoco@linaro.org> >>> --- >>> arch/arm/include/asm/pgtable-2level-types.h | 2 ++ >>> arch/arm/include/asm/pgtable-3level-types.h | 2 ++ >>> arch/arm64/include/asm/pgtable-types.h | 2 ++ >>> arch/ia64/include/asm/page.h | 2 ++ >>> arch/mips/include/asm/page.h | 2 ++ >>> arch/powerpc/include/asm/mmu.h | 2 ++ >>> arch/s390/include/asm/page.h | 2 ++ >>> arch/sh/include/asm/page.h | 2 ++ >>> arch/sparc/include/asm/page_32.h | 2 ++ >>> arch/sparc/include/asm/page_64.h | 2 ++ >>> arch/x86/include/asm/pgtable-2level_types.h | 2 ++ >>> arch/x86/include/asm/pgtable-3level_types.h | 3 +- >>> arch/x86/include/asm/pgtable_64_types.h | 4 +-- >>> mm/zsmalloc.c | 35 +++++++++++---------- >>> 14 files changed, 45 insertions(+), 19 deletions(-) >>> >>> diff --git a/arch/arm/include/asm/pgtable-2level-types.h b/arch/arm/include/asm/pgtable-2level-types.h >>> index 66cb5b0e89c5..552dba411324 100644 >>> --- a/arch/arm/include/asm/pgtable-2level-types.h >>> +++ b/arch/arm/include/asm/pgtable-2level-types.h >>> @@ -64,4 +64,6 @@ typedef pteval_t pgprot_t; >>> #endif /* STRICT_MM_TYPECHECKS */ >>> +#define MAX_POSSIBLE_PHYSMEM_BITS 32 >>> + >>> #endif /* _ASM_PGTABLE_2LEVEL_TYPES_H */ >>> diff --git a/arch/arm/include/asm/pgtable-3level-types.h b/arch/arm/include/asm/pgtable-3level-types.h >>> index 921aa30259c4..664c39e6517c 100644 >>> --- a/arch/arm/include/asm/pgtable-3level-types.h >>> +++ b/arch/arm/include/asm/pgtable-3level-types.h >>> @@ -67,4 +67,6 @@ typedef pteval_t pgprot_t; >>> #endif /* STRICT_MM_TYPECHECKS */ >>> +#define MAX_POSSIBLE_PHYSMEM_BITS 36 >> >> Nit: with LPAE, physical addresses go up to 40 bits, not just 36. Hum, I got it from where it was being defined when having SPARSEMEM enabled (#define MAX_PHYSMEM_BITS 36 in arch/arm/include/asm/sparsemem.h), since without SPARSEMEM it would default to BITS_PER_LONG. > Right, with that set at 40, we get: > > #define _PFN_BITS (MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT) > > == 28 > > #define OBJ_TAG_BITS 1 > #define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS) > > == 3 > > #define ZS_MAX_ZSPAGE_ORDER 2 > #define ZS_MAX_PAGES_PER_ZSPAGE (_AC(1, UL) << ZS_MAX_ZSPAGE_ORDER) > > == 4 > > #define ZS_MIN_ALLOC_SIZE \ > MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS)) > > == 4 << 12 >> 3 = 2048 > > or half-page allocations. > > Given this in Documentation/vm/zsmalloc.rst: > > On the other hand, if we just use single > (0-order) pages, it would suffer from very high fragmentation -- > any object of size PAGE_SIZE/2 or larger would occupy an entire page. > This was one of the major issues with its predecessor (xvmalloc). > > It seems that would not be acceptable, so I have to ask whether > using an unsigned long to store PFN + object ID is really acceptable. > Maybe the real solution to this problem is to stop using an > unsigned long to contain both the PFN and object ID? >
Hi Rafael,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on linus/master]
[also build test ERROR on v4.20-rc6 next-20181212]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Rafael-David-Tinoco/mm-zsmalloc-c-Fix-zsmalloc-32-bit-PAE-support/20181211-020704
config: mips-allmodconfig (attached as .config)
compiler: mips-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
GCC_VERSION=7.2.0 make.cross ARCH=mips
All error/warnings (new ones prefixed by >>):
>> mm/zsmalloc.c:116:5: error: #error "MAX_POSSIBLE_PHYSMEM_BITS is wrong for this arch";
#error "MAX_POSSIBLE_PHYSMEM_BITS is wrong for this arch";
^~~~~
In file included from include/linux/cache.h:5:0,
from arch/mips/include/asm/cpu-info.h:15,
from arch/mips/include/asm/cpu-features.h:13,
from arch/mips/include/asm/bitops.h:21,
from include/linux/bitops.h:19,
from include/linux/kernel.h:11,
from include/linux/list.h:9,
from include/linux/module.h:9,
from mm/zsmalloc.c:33:
>> mm/zsmalloc.c:133:49: warning: right shift count is negative [-Wshift-count-negative]
MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
^
include/uapi/linux/kernel.h:13:40: note: in definition of macro '__KERNEL_DIV_ROUND_UP'
#define __KERNEL_DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
^
>> mm/zsmalloc.c:133:2: note: in expansion of macro 'MAX'
MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
^~~
>> mm/zsmalloc.c:151:59: note: in expansion of macro 'ZS_MIN_ALLOC_SIZE'
#define ZS_SIZE_CLASSES (DIV_ROUND_UP(ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE, \
^~~~~~~~~~~~~~~~~
>> mm/zsmalloc.c:256:32: note: in expansion of macro 'ZS_SIZE_CLASSES'
struct size_class *size_class[ZS_SIZE_CLASSES];
^~~~~~~~~~~~~~~
>> mm/zsmalloc.c:133:49: warning: right shift count is negative [-Wshift-count-negative]
MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
^
include/uapi/linux/kernel.h:13:40: note: in definition of macro '__KERNEL_DIV_ROUND_UP'
#define __KERNEL_DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
^
>> mm/zsmalloc.c:133:2: note: in expansion of macro 'MAX'
MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
^~~
>> mm/zsmalloc.c:151:59: note: in expansion of macro 'ZS_MIN_ALLOC_SIZE'
#define ZS_SIZE_CLASSES (DIV_ROUND_UP(ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE, \
^~~~~~~~~~~~~~~~~
>> mm/zsmalloc.c:256:32: note: in expansion of macro 'ZS_SIZE_CLASSES'
struct size_class *size_class[ZS_SIZE_CLASSES];
^~~~~~~~~~~~~~~
>> mm/zsmalloc.c:256:21: error: variably modified 'size_class' at file scope
struct size_class *size_class[ZS_SIZE_CLASSES];
^~~~~~~~~~
In file included from include/linux/kernel.h:10:0,
from include/linux/list.h:9,
from include/linux/module.h:9,
from mm/zsmalloc.c:33:
mm/zsmalloc.c: In function 'get_size_class_index':
>> mm/zsmalloc.c:133:49: warning: right shift count is negative [-Wshift-count-negative]
MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
^
include/linux/compiler.h:76:40: note: in definition of macro 'likely'
# define likely(x) __builtin_expect(!!(x), 1)
^
>> mm/zsmalloc.c:133:2: note: in expansion of macro 'MAX'
MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
^~~
mm/zsmalloc.c:543:20: note: in expansion of macro 'ZS_MIN_ALLOC_SIZE'
if (likely(size > ZS_MIN_ALLOC_SIZE))
^~~~~~~~~~~~~~~~~
>> mm/zsmalloc.c:133:49: warning: right shift count is negative [-Wshift-count-negative]
MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
^
include/linux/compiler.h:76:40: note: in definition of macro 'likely'
# define likely(x) __builtin_expect(!!(x), 1)
^
>> mm/zsmalloc.c:133:2: note: in expansion of macro 'MAX'
MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
^~~
mm/zsmalloc.c:543:20: note: in expansion of macro 'ZS_MIN_ALLOC_SIZE'
if (likely(size > ZS_MIN_ALLOC_SIZE))
^~~~~~~~~~~~~~~~~
In file included from include/linux/cache.h:5:0,
from arch/mips/include/asm/cpu-info.h:15,
from arch/mips/include/asm/cpu-features.h:13,
from arch/mips/include/asm/bitops.h:21,
from include/linux/bitops.h:19,
from include/linux/kernel.h:11,
from include/linux/list.h:9,
from include/linux/module.h:9,
from mm/zsmalloc.c:33:
>> mm/zsmalloc.c:133:49: warning: right shift count is negative [-Wshift-count-negative]
MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
^
include/uapi/linux/kernel.h:13:40: note: in definition of macro '__KERNEL_DIV_ROUND_UP'
#define __KERNEL_DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
^
>> mm/zsmalloc.c:133:2: note: in expansion of macro 'MAX'
MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
^~~
mm/zsmalloc.c:544:29: note: in expansion of macro 'ZS_MIN_ALLOC_SIZE'
idx = DIV_ROUND_UP(size - ZS_MIN_ALLOC_SIZE,
^~~~~~~~~~~~~~~~~
>> mm/zsmalloc.c:133:49: warning: right shift count is negative [-Wshift-count-negative]
MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
^
include/uapi/linux/kernel.h:13:40: note: in definition of macro '__KERNEL_DIV_ROUND_UP'
#define __KERNEL_DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
^
>> mm/zsmalloc.c:133:2: note: in expansion of macro 'MAX'
MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
^~~
mm/zsmalloc.c:544:29: note: in expansion of macro 'ZS_MIN_ALLOC_SIZE'
idx = DIV_ROUND_UP(size - ZS_MIN_ALLOC_SIZE,
^~~~~~~~~~~~~~~~~
In file included from include/linux/list.h:9:0,
from include/linux/module.h:9,
from mm/zsmalloc.c:33:
>> mm/zsmalloc.c:133:49: warning: right shift count is negative [-Wshift-count-negative]
MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
^
include/linux/kernel.h:861:27: note: in definition of macro '__cmp'
#define __cmp(x, y, op) ((x) op (y) ? (x) : (y))
^
include/linux/kernel.h:937:27: note: in expansion of macro '__careful_cmp'
#define min_t(type, x, y) __careful_cmp((type)(x), (type)(y), <)
^~~~~~~~~~~~~
>> mm/zsmalloc.c:547:9: note: in expansion of macro 'min_t'
return min_t(int, ZS_SIZE_CLASSES - 1, idx);
^~~~~
vim +116 mm/zsmalloc.c
32
> 33 #include <linux/module.h>
34 #include <linux/kernel.h>
35 #include <linux/sched.h>
36 #include <linux/magic.h>
37 #include <linux/bitops.h>
38 #include <linux/errno.h>
39 #include <linux/highmem.h>
40 #include <linux/string.h>
41 #include <linux/slab.h>
42 #include <asm/tlbflush.h>
43 #include <asm/pgtable.h>
44 #include <linux/cpumask.h>
45 #include <linux/cpu.h>
46 #include <linux/vmalloc.h>
47 #include <linux/preempt.h>
48 #include <linux/spinlock.h>
49 #include <linux/shrinker.h>
50 #include <linux/types.h>
51 #include <linux/debugfs.h>
52 #include <linux/zsmalloc.h>
53 #include <linux/zpool.h>
54 #include <linux/mount.h>
55 #include <linux/migrate.h>
56 #include <linux/pagemap.h>
57 #include <linux/fs.h>
58
59 #define ZSPAGE_MAGIC 0x58
60
61 /*
62 * This must be power of 2 and greater than of equal to sizeof(link_free).
63 * These two conditions ensure that any 'struct link_free' itself doesn't
64 * span more than 1 page which avoids complex case of mapping 2 pages simply
65 * to restore link_free pointer values.
66 */
67 #define ZS_ALIGN 8
68
69 /*
70 * A single 'zspage' is composed of up to 2^N discontiguous 0-order (single)
71 * pages. ZS_MAX_ZSPAGE_ORDER defines upper limit on N.
72 */
73 #define ZS_MAX_ZSPAGE_ORDER 2
74 #define ZS_MAX_PAGES_PER_ZSPAGE (_AC(1, UL) << ZS_MAX_ZSPAGE_ORDER)
75
76 #define ZS_HANDLE_SIZE (sizeof(unsigned long))
77
78 /*
79 * Object location (<PFN>, <obj_idx>) is encoded as
80 * as single (unsigned long) handle value.
81 *
82 * Note that object index <obj_idx> starts from 0.
83 */
84
85 /*
86 * Memory for allocating for handle keeps object position by
87 * encoding <page, obj_idx> and the encoded value has a room
88 * in least bit(ie, look at obj_to_location).
89 * We use the bit to synchronize between object access by
90 * user and migration.
91 */
92 #define HANDLE_PIN_BIT 0
93
94 /*
95 * Head in allocated object should have OBJ_ALLOCATED_TAG
96 * to identify the object was allocated or not.
97 * It's okay to add the status bit in the least bit because
98 * header keeps handle which is 4byte-aligned address so we
99 * have room for two bit at least.
100 */
101 #define OBJ_ALLOCATED_TAG 1
102 #define OBJ_TAG_BITS 1
103
104 /*
105 * MAX_POSSIBLE_PHYSMEM_BITS should be defined by all archs using zsmalloc:
106 * Trying to guess it from MAX_PHYSMEM_BITS, or considering it BITS_PER_LONG,
107 * proved to be wrong by not considering PAE capabilities, or using SPARSEMEM
108 * only headers, leading to bad object encoding due to object index overflow.
109 */
110 #ifndef MAX_POSSIBLE_PHYSMEM_BITS
111 #define MAX_POSSIBLE_PHYSMEM_BITS BITS_PER_LONG
112 #error "MAX_POSSIBLE_PHYSMEM_BITS HAS to be defined by arch using zsmalloc";
113 #else
114 #ifndef CONFIG_64BIT
115 #if (MAX_POSSIBLE_PHYSMEM_BITS >= (BITS_PER_LONG + PAGE_SHIFT - OBJ_TAG_BITS))
> 116 #error "MAX_POSSIBLE_PHYSMEM_BITS is wrong for this arch";
117 #endif
118 #endif
119 #endif
120
121 #define _PFN_BITS (MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT)
122 #define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS)
> 123 #define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1)
124
125 #define FULLNESS_BITS 2
126 #define CLASS_BITS 8
127 #define ISOLATED_BITS 3
128 #define MAGIC_VAL_BITS 8
129
130 #define MAX(a, b) ((a) >= (b) ? (a) : (b))
131 /* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */
132 #define ZS_MIN_ALLOC_SIZE \
> 133 MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
134 /* each chunk includes extra space to keep handle */
135 #define ZS_MAX_ALLOC_SIZE PAGE_SIZE
136
137 /*
138 * On systems with 4K page size, this gives 255 size classes! There is a
139 * trader-off here:
140 * - Large number of size classes is potentially wasteful as free page are
141 * spread across these classes
142 * - Small number of size classes causes large internal fragmentation
143 * - Probably its better to use specific size classes (empirically
144 * determined). NOTE: all those class sizes must be set as multiple of
145 * ZS_ALIGN to make sure link_free itself never has to span 2 pages.
146 *
147 * ZS_MIN_ALLOC_SIZE and ZS_SIZE_CLASS_DELTA must be multiple of ZS_ALIGN
148 * (reason above)
149 */
150 #define ZS_SIZE_CLASS_DELTA (PAGE_SIZE >> CLASS_BITS)
> 151 #define ZS_SIZE_CLASSES (DIV_ROUND_UP(ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE, \
152 ZS_SIZE_CLASS_DELTA) + 1)
153
154 enum fullness_group {
155 ZS_EMPTY,
156 ZS_ALMOST_EMPTY,
157 ZS_ALMOST_FULL,
158 ZS_FULL,
159 NR_ZS_FULLNESS,
160 };
161
162 enum zs_stat_type {
163 CLASS_EMPTY,
164 CLASS_ALMOST_EMPTY,
165 CLASS_ALMOST_FULL,
166 CLASS_FULL,
167 OBJ_ALLOCATED,
168 OBJ_USED,
169 NR_ZS_STAT_TYPE,
170 };
171
172 struct zs_size_stat {
173 unsigned long objs[NR_ZS_STAT_TYPE];
174 };
175
176 #ifdef CONFIG_ZSMALLOC_STAT
177 static struct dentry *zs_stat_root;
178 #endif
179
180 #ifdef CONFIG_COMPACTION
181 static struct vfsmount *zsmalloc_mnt;
182 #endif
183
184 /*
185 * We assign a page to ZS_ALMOST_EMPTY fullness group when:
186 * n <= N / f, where
187 * n = number of allocated objects
188 * N = total number of objects zspage can store
189 * f = fullness_threshold_frac
190 *
191 * Similarly, we assign zspage to:
192 * ZS_ALMOST_FULL when n > N / f
193 * ZS_EMPTY when n == 0
194 * ZS_FULL when n == N
195 *
196 * (see: fix_fullness_group())
197 */
198 static const int fullness_threshold_frac = 4;
199 static size_t huge_class_size;
200
201 struct size_class {
202 spinlock_t lock;
203 struct list_head fullness_list[NR_ZS_FULLNESS];
204 /*
205 * Size of objects stored in this class. Must be multiple
206 * of ZS_ALIGN.
207 */
208 int size;
209 int objs_per_zspage;
210 /* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
211 int pages_per_zspage;
212
213 unsigned int index;
214 struct zs_size_stat stats;
215 };
216
217 /* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */
218 static void SetPageHugeObject(struct page *page)
219 {
220 SetPageOwnerPriv1(page);
221 }
222
223 static void ClearPageHugeObject(struct page *page)
224 {
225 ClearPageOwnerPriv1(page);
226 }
227
228 static int PageHugeObject(struct page *page)
229 {
230 return PageOwnerPriv1(page);
231 }
232
233 /*
234 * Placed within free objects to form a singly linked list.
235 * For every zspage, zspage->freeobj gives head of this list.
236 *
237 * This must be power of 2 and less than or equal to ZS_ALIGN
238 */
239 struct link_free {
240 union {
241 /*
242 * Free object index;
243 * It's valid for non-allocated object
244 */
245 unsigned long next;
246 /*
247 * Handle of allocated object.
248 */
249 unsigned long handle;
250 };
251 };
252
253 struct zs_pool {
254 const char *name;
255
> 256 struct size_class *size_class[ZS_SIZE_CLASSES];
257 struct kmem_cache *handle_cachep;
258 struct kmem_cache *zspage_cachep;
259
260 atomic_long_t pages_allocated;
261
262 struct zs_pool_stats stats;
263
264 /* Compact classes */
265 struct shrinker shrinker;
266
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
Hi Rafael,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on linus/master]
[also build test ERROR on v4.20-rc6 next-20181212]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Rafael-David-Tinoco/mm-zsmalloc-c-Fix-zsmalloc-32-bit-PAE-support/20181211-020704
config: xtensa-allmodconfig (attached as .config)
compiler: xtensa-linux-gcc (GCC) 8.1.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
GCC_VERSION=8.1.0 make.cross ARCH=xtensa
All errors (new ones prefixed by >>):
>> mm/zsmalloc.c:112:3: error: #error "MAX_POSSIBLE_PHYSMEM_BITS HAS to be defined by arch using zsmalloc";
#error "MAX_POSSIBLE_PHYSMEM_BITS HAS to be defined by arch using zsmalloc";
^~~~~
vim +112 mm/zsmalloc.c
103
104 /*
105 * MAX_POSSIBLE_PHYSMEM_BITS should be defined by all archs using zsmalloc:
106 * Trying to guess it from MAX_PHYSMEM_BITS, or considering it BITS_PER_LONG,
107 * proved to be wrong by not considering PAE capabilities, or using SPARSEMEM
108 * only headers, leading to bad object encoding due to object index overflow.
109 */
110 #ifndef MAX_POSSIBLE_PHYSMEM_BITS
111 #define MAX_POSSIBLE_PHYSMEM_BITS BITS_PER_LONG
> 112 #error "MAX_POSSIBLE_PHYSMEM_BITS HAS to be defined by arch using zsmalloc";
113 #else
114 #ifndef CONFIG_64BIT
115 #if (MAX_POSSIBLE_PHYSMEM_BITS >= (BITS_PER_LONG + PAGE_SHIFT - OBJ_TAG_BITS))
116 #error "MAX_POSSIBLE_PHYSMEM_BITS is wrong for this arch";
117 #endif
118 #endif
119 #endif
120
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
diff --git a/arch/arm/include/asm/pgtable-2level-types.h b/arch/arm/include/asm/pgtable-2level-types.h index 66cb5b0e89c5..552dba411324 100644 --- a/arch/arm/include/asm/pgtable-2level-types.h +++ b/arch/arm/include/asm/pgtable-2level-types.h @@ -64,4 +64,6 @@ typedef pteval_t pgprot_t; #endif /* STRICT_MM_TYPECHECKS */ +#define MAX_POSSIBLE_PHYSMEM_BITS 32 + #endif /* _ASM_PGTABLE_2LEVEL_TYPES_H */ diff --git a/arch/arm/include/asm/pgtable-3level-types.h b/arch/arm/include/asm/pgtable-3level-types.h index 921aa30259c4..664c39e6517c 100644 --- a/arch/arm/include/asm/pgtable-3level-types.h +++ b/arch/arm/include/asm/pgtable-3level-types.h @@ -67,4 +67,6 @@ typedef pteval_t pgprot_t; #endif /* STRICT_MM_TYPECHECKS */ +#define MAX_POSSIBLE_PHYSMEM_BITS 36 + #endif /* _ASM_PGTABLE_3LEVEL_TYPES_H */ diff --git a/arch/arm64/include/asm/pgtable-types.h b/arch/arm64/include/asm/pgtable-types.h index 345a072b5856..45c3834eb4c8 100644 --- a/arch/arm64/include/asm/pgtable-types.h +++ b/arch/arm64/include/asm/pgtable-types.h @@ -64,4 +64,6 @@ typedef struct { pteval_t pgprot; } pgprot_t; #include <asm-generic/5level-fixup.h> #endif +#define MAX_POSSIBLE_PHYSMEM_BITS CONFIG_ARM64_PA_BITS + #endif /* __ASM_PGTABLE_TYPES_H */ diff --git a/arch/ia64/include/asm/page.h b/arch/ia64/include/asm/page.h index 5798bd2b462c..a3e055979e46 100644 --- a/arch/ia64/include/asm/page.h +++ b/arch/ia64/include/asm/page.h @@ -235,4 +235,6 @@ get_order (unsigned long size) #define __HAVE_ARCH_GATE_AREA 1 +#define MAX_POSSIBLE_PHYSMEM_BITS 50 + #endif /* _ASM_IA64_PAGE_H */ diff --git a/arch/mips/include/asm/page.h b/arch/mips/include/asm/page.h index e8cc328fce2d..f6a5dea1a66c 100644 --- a/arch/mips/include/asm/page.h +++ b/arch/mips/include/asm/page.h @@ -263,4 +263,6 @@ extern int __virt_addr_valid(const volatile void *kaddr); #include <asm-generic/memory_model.h> #include <asm-generic/getorder.h> +#define MAX_POSSIBLE_PHYSMEM_BITS 48 + #endif /* _ASM_PAGE_H */ diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h index eb20eb3b8fb0..2ebc1d2d9a5c 100644 --- a/arch/powerpc/include/asm/mmu.h +++ b/arch/powerpc/include/asm/mmu.h @@ -324,6 +324,8 @@ static inline u16 get_mm_addr_key(struct mm_struct *mm, unsigned long address) #define MAX_PHYSMEM_BITS 46 #endif +#define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS + #ifdef CONFIG_PPC_BOOK3S_64 #include <asm/book3s/64/mmu.h> #else /* CONFIG_PPC_BOOK3S_64 */ diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h index a4d38092530a..8abec1461bf7 100644 --- a/arch/s390/include/asm/page.h +++ b/arch/s390/include/asm/page.h @@ -180,4 +180,6 @@ static inline int devmem_is_allowed(unsigned long pfn) #include <asm-generic/memory_model.h> #include <asm-generic/getorder.h> +#define MAX_POSSIBLE_PHYSMEM_BITS CONFIG_MAX_PHYSMEM_BITS + #endif /* _S390_PAGE_H */ diff --git a/arch/sh/include/asm/page.h b/arch/sh/include/asm/page.h index 5eef8be3e59f..40c7e12cf09e 100644 --- a/arch/sh/include/asm/page.h +++ b/arch/sh/include/asm/page.h @@ -205,4 +205,6 @@ typedef struct page *pgtable_t; #define ARCH_SLAB_MINALIGN 8 #endif +#define MAX_POSSIBLE_PHYSMEM_BITS 32 + #endif /* __ASM_SH_PAGE_H */ diff --git a/arch/sparc/include/asm/page_32.h b/arch/sparc/include/asm/page_32.h index b76d59edec8c..14e9ca4659d7 100644 --- a/arch/sparc/include/asm/page_32.h +++ b/arch/sparc/include/asm/page_32.h @@ -139,4 +139,6 @@ extern unsigned long pfn_base; #include <asm-generic/memory_model.h> #include <asm-generic/getorder.h> +#define MAX_POSSIBLE_PHYSMEM_BITS 32 + #endif /* _SPARC_PAGE_H */ diff --git a/arch/sparc/include/asm/page_64.h b/arch/sparc/include/asm/page_64.h index e80f2d5bf62f..6d6f3654ead1 100644 --- a/arch/sparc/include/asm/page_64.h +++ b/arch/sparc/include/asm/page_64.h @@ -163,4 +163,6 @@ extern unsigned long PAGE_OFFSET; #include <asm-generic/getorder.h> +#define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYS_ADDRESS_BITS + #endif /* _SPARC64_PAGE_H */ diff --git a/arch/x86/include/asm/pgtable-2level_types.h b/arch/x86/include/asm/pgtable-2level_types.h index 6deb6cd236e3..c2eae59e6505 100644 --- a/arch/x86/include/asm/pgtable-2level_types.h +++ b/arch/x86/include/asm/pgtable-2level_types.h @@ -38,4 +38,6 @@ typedef union { /* This covers all VMSPLIT_* and VMSPLIT_*_OPT variants */ #define PGD_KERNEL_START (CONFIG_PAGE_OFFSET >> PGDIR_SHIFT) +#define MAX_POSSIBLE_PHYSMEM_BITS 32 + #endif /* _ASM_X86_PGTABLE_2LEVEL_DEFS_H */ diff --git a/arch/x86/include/asm/pgtable-3level_types.h b/arch/x86/include/asm/pgtable-3level_types.h index 33845d36897c..5fce514a49a0 100644 --- a/arch/x86/include/asm/pgtable-3level_types.h +++ b/arch/x86/include/asm/pgtable-3level_types.h @@ -45,7 +45,8 @@ typedef union { */ #define PTRS_PER_PTE 512 -#define MAX_POSSIBLE_PHYSMEM_BITS 36 #define PGD_KERNEL_START (CONFIG_PAGE_OFFSET >> PGDIR_SHIFT) +#define MAX_POSSIBLE_PHYSMEM_BITS 36 + #endif /* _ASM_X86_PGTABLE_3LEVEL_DEFS_H */ diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h index 84bd9bdc1987..d808cfde3d19 100644 --- a/arch/x86/include/asm/pgtable_64_types.h +++ b/arch/x86/include/asm/pgtable_64_types.h @@ -64,8 +64,6 @@ extern unsigned int ptrs_per_p4d; #define P4D_SIZE (_AC(1, UL) << P4D_SHIFT) #define P4D_MASK (~(P4D_SIZE - 1)) -#define MAX_POSSIBLE_PHYSMEM_BITS 52 - #else /* CONFIG_X86_5LEVEL */ /* @@ -154,4 +152,6 @@ extern unsigned int ptrs_per_p4d; #define PGD_KERNEL_START ((PAGE_SIZE / 2) / sizeof(pgd_t)) +#define MAX_POSSIBLE_PHYSMEM_BITS (pgtable_l5_enabled() ? 52 : 46) + #endif /* _ASM_X86_PGTABLE_64_DEFS_H */ diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index 0787d33b80d8..132c20b6fd4f 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -80,23 +80,7 @@ * as single (unsigned long) handle value. * * Note that object index <obj_idx> starts from 0. - * - * This is made more complicated by various memory models and PAE. - */ - -#ifndef MAX_POSSIBLE_PHYSMEM_BITS -#ifdef MAX_PHYSMEM_BITS -#define MAX_POSSIBLE_PHYSMEM_BITS MAX_PHYSMEM_BITS -#else -/* - * If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just - * be PAGE_SHIFT */ -#define MAX_POSSIBLE_PHYSMEM_BITS BITS_PER_LONG -#endif -#endif - -#define _PFN_BITS (MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT) /* * Memory for allocating for handle keeps object position by @@ -116,6 +100,25 @@ */ #define OBJ_ALLOCATED_TAG 1 #define OBJ_TAG_BITS 1 + +/* + * MAX_POSSIBLE_PHYSMEM_BITS should be defined by all archs using zsmalloc: + * Trying to guess it from MAX_PHYSMEM_BITS, or considering it BITS_PER_LONG, + * proved to be wrong by not considering PAE capabilities, or using SPARSEMEM + * only headers, leading to bad object encoding due to object index overflow. + */ +#ifndef MAX_POSSIBLE_PHYSMEM_BITS + #define MAX_POSSIBLE_PHYSMEM_BITS BITS_PER_LONG + #error "MAX_POSSIBLE_PHYSMEM_BITS HAS to be defined by arch using zsmalloc"; +#else + #ifndef CONFIG_64BIT + #if (MAX_POSSIBLE_PHYSMEM_BITS >= (BITS_PER_LONG + PAGE_SHIFT - OBJ_TAG_BITS)) + #error "MAX_POSSIBLE_PHYSMEM_BITS is wrong for this arch"; + #endif + #endif +#endif + +#define _PFN_BITS (MAX_POSSIBLE_PHYSMEM_BITS - PAGE_SHIFT) #define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS) #define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1)
On 32-bit systems, zsmalloc uses HIGHMEM and, when PAE is enabled, the physical frame number might be so big that zsmalloc obj encoding (to location) will break, causing: BUG: KASAN: null-ptr-deref in zs_map_object+0xa4/0x2bc Read of size 4 at addr 00000000 by task mkfs.ext4/623 CPU: 2 PID: 623 Comm: mkfs.ext4 Not tainted 4.19.0-rc8-00017-g8239bc6d3307-dirty #15 Hardware name: Generic DT based system [<c0418f7c>] (unwind_backtrace) from [<c0410ca4>] (show_stack+0x20/0x24) [<c0410ca4>] (show_stack) from [<c16bd540>] (dump_stack+0xbc/0xe8) [<c16bd540>] (dump_stack) from [<c06cab74>] (kasan_report+0x248/0x390) [<c06cab74>] (kasan_report) from [<c06c94e8>] (__asan_load4+0x78/0xb4) [<c06c94e8>] (__asan_load4) from [<c06ddc24>] (zs_map_object+0xa4/0x2bc) [<c06ddc24>] (zs_map_object) from [<bf0bbbd8>] (zram_bvec_rw.constprop.2+0x324/0x8e4 [zram]) [<bf0bbbd8>] (zram_bvec_rw.constprop.2 [zram]) from [<bf0bc3cc>] (zram_make_request+0x234/0x46c [zram]) [<bf0bc3cc>] (zram_make_request [zram]) from [<c09aff9c>] (generic_make_request+0x304/0x63c) [<c09aff9c>] (generic_make_request) from [<c09b0320>] (submit_bio+0x4c/0x1c8) [<c09b0320>] (submit_bio) from [<c0743570>] (submit_bh_wbc.constprop.15+0x238/0x26c) [<c0743570>] (submit_bh_wbc.constprop.15) from [<c0746cf8>] (__block_write_full_page+0x524/0x76c) [<c0746cf8>] (__block_write_full_page) from [<c07472c4>] (block_write_full_page+0x1bc/0x1d4) [<c07472c4>] (block_write_full_page) from [<c0748eb4>] (blkdev_writepage+0x24/0x28) [<c0748eb4>] (blkdev_writepage) from [<c064a780>] (__writepage+0x44/0x78) [<c064a780>] (__writepage) from [<c064b50c>] (write_cache_pages+0x3b8/0x800) [<c064b50c>] (write_cache_pages) from [<c064dd78>] (generic_writepages+0x74/0xa0) [<c064dd78>] (generic_writepages) from [<c0748e64>] (blkdev_writepages+0x18/0x1c) [<c0748e64>] (blkdev_writepages) from [<c064e890>] (do_writepages+0x68/0x134) [<c064e890>] (do_writepages) from [<c06368a4>] (__filemap_fdatawrite_range+0xb0/0xf4) [<c06368a4>] (__filemap_fdatawrite_range) from [<c0636b68>] (file_write_and_wait_range+0x64/0xd0) [<c0636b68>] (file_write_and_wait_range) from [<c0747af8>] (blkdev_fsync+0x54/0x84) [<c0747af8>] (blkdev_fsync) from [<c0739dac>] (vfs_fsync_range+0x70/0xd4) [<c0739dac>] (vfs_fsync_range) from [<c0739e98>] (do_fsync+0x4c/0x80) [<c0739e98>] (do_fsync) from [<c073a26c>] (sys_fsync+0x1c/0x20) [<c073a26c>] (sys_fsync) from [<c0401000>] (ret_fast_syscall+0x0/0x2c) when trying to decode (the pfn) and map the object. That happens because one architecture might not re-define MAX_PHYSMEM_BITS, like in this ARM 32-bit w/ LPAE enabled example. For 32-bit systems, if not re-defined, MAX_POSSIBLE_PHYSMEM_BITS will default to BITS_PER_LONG (32) in most cases, and, with PAE enabled, _PFN_BITS might be wrong: which may cause obj variable to overflow if frame number is in HIGHMEM and referencing a page above the 4GB watermark. commit 6e00ec00b1a7 ("staging: zsmalloc: calculate MAX_PHYSMEM_BITS if not defined") realized MAX_PHYSMEM_BITS depended on SPARSEMEM headers and "fixed" it by calculating it using BITS_PER_LONG if SPARSEMEM wasn't used, like in the example given above. Systems with potential for PAE exist for a long time and assuming BITS_PER_LONG seems inadequate. Defining MAX_PHYSMEM_BITS looks better, however it is NOT a constant anymore for x86. SO, instead, MAX_POSSIBLE_PHYSMEM_BITS should be defined by every architecture using zsmalloc, together with a sanity check for MAX_POSSIBLE_PHYSMEM_BITS being too big on 32-bit systems. Link: https://bugs.linaro.org/show_bug.cgi?id=3765#c17 Signed-off-by: Rafael David Tinoco <rafael.tinoco@linaro.org> --- arch/arm/include/asm/pgtable-2level-types.h | 2 ++ arch/arm/include/asm/pgtable-3level-types.h | 2 ++ arch/arm64/include/asm/pgtable-types.h | 2 ++ arch/ia64/include/asm/page.h | 2 ++ arch/mips/include/asm/page.h | 2 ++ arch/powerpc/include/asm/mmu.h | 2 ++ arch/s390/include/asm/page.h | 2 ++ arch/sh/include/asm/page.h | 2 ++ arch/sparc/include/asm/page_32.h | 2 ++ arch/sparc/include/asm/page_64.h | 2 ++ arch/x86/include/asm/pgtable-2level_types.h | 2 ++ arch/x86/include/asm/pgtable-3level_types.h | 3 +- arch/x86/include/asm/pgtable_64_types.h | 4 +-- mm/zsmalloc.c | 35 +++++++++++---------- 14 files changed, 45 insertions(+), 19 deletions(-)