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On 2023/10/13 14:03, 陈冠有 wrote:
> Hi Kazu
>
> Thank you for your advice.
>
>
>> Does this mean that the current "memset(buf, entry, len)" is a bug,
>> because entry is ulong, right? If so, I agree.
>
>
> Yes.
>
>
> Subject: [PATCH] Fix: "rd" command to read zram buf on Linux 5.17 and later
>
> Kernel commit a41ec880aa7b ("zsmalloc: move huge compressed obj from page to zspage"),
> which is contained in Linux 5.17 and later kernels. Use zspage_5_17 to be compatible with later versions.
>
> Kernel commit ffedd09fa9b06 ("zsmalloc: Stop using slab fields in struct page"),
> page->index and page->freelist are at the same offset in struct page.
>
> Kernel commit f635725c3905e ("zram: do not waste zram_table_entry flags bits"),
> which is contained in Linux 6.1 and later kernels. let ZRAM_FLAG_SHIFT follow ZRAM_LOCK.
>
> Before:
> crash> mod -s zram zram.ko
> MODULE NAME BASE SIZE OBJECT FILE
> ffffffde224db800 zram ffffffde224d2000 57344 zram.ko
> crash> mod -s zsmalloc zsmalloc.ko
> MODULE NAME BASE SIZE OBJECT FILE
> ffffffde224c5180 zsmalloc ffffffde224bf000 40960 zsmalloc.ko
> crash> rd 0x13d89fb0
> rd: zspage magic incorrect: b0
>
> After:
> crash> rd 0x13d89fb0
> 13d89fb0: c2b54f7170883b20 ;.pqO..
>
> Link:
https://lkml.kernel.org/r/20211115185909.3949505-6-minchan@kernel.org
> Link:
https://lkml.kernel.org/r/20220912152744.527438-1-senozhatsky@chromium.org
>
> Signed-off-by: chenguanyou <chenguanyou@xiaomi.com>
> ---
> defs.h | 26 +++++++++++++++++++++
> diskdump.c | 66 ++++++++++++++++++++++++++++++++++++++++++++----------
> 2 files changed, 80 insertions(+), 12 deletions(-)
>
> diff --git a/defs.h b/defs.h
> index 96a7a2a..2038351 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -2225,6 +2225,7 @@ struct offset_table { /* stash of commonly-used offsets */
> long module_memory_base;
> long module_memory_size;
> long irq_data_irq;
> + long zspage_huge;
> };
>
> struct size_table { /* stash of commonly-used sizes */
> @@ -7210,6 +7211,19 @@ ulong try_zram_decompress(ulonglong pte_val, unsigned char *buf, ulong len, ulon
> #define SECTORS_PER_PAGE (1 << SECTORS_PER_PAGE_SHIFT)
> #define ZRAM_FLAG_SHIFT (1<<24)
> #define ZRAM_FLAG_SAME_BIT (1<<25)
> +
> +struct zram_pageflags {
> + long ZRAM_LOCK;
> + long ZRAM_SAME;
> +};
> +
> +/*
> + * diskdump.c
> + */
> +extern struct zram_pageflags zram_pageflags;
> +#define ZRAM_PAGEFLAG_INIT(X, Y) (zram_pageflags.X = Y)
> +#define ZRAM_PAGEFLAG_VALUE(X) (zram_pageflags.X)
Thank you for the update.
I don't think these macros are necessary, so simplified the patch on my
end. With rethinking the names, kept "ZRAM_FLAG_SHIFT" and
"ZRAM_FLAG_SAME_BIT" as they are, and made some tweaks.
Guanyou and Lianbo, is this attached patch OK?
I tested this on Linux 6.1.
crash> vtop 00007fb60be00000
VIRTUAL PHYSICAL
7fb60be00000 (not mapped)
PGD: 108e807f8 => 1107c4067
PUD: 1107c46c0 => 106ec9067
PMD: 106ec92f8 => 1060f2067
PTE: 1060f2000 => 7fffffffdfffe0a
PTE SWAP OFFSET
7fffffffdfffe0a /dev/zram0 65536
VMA START END FLAGS FILE
ffff935206cda980 7fb60bdfe000 7fb64be00000 8100073
SWAP: /dev/zram0 OFFSET: 65536
crash> rd 00007fb60be00000
7fb60be00000: 0000000000001000 ........
(Note that it looks like Linux 6.2 and later have other changes related
to zram, so this patch supports up to 6.1. We can fix them later.)
Thanks,
Kazu
> +
> struct zspage {
> struct {
> unsigned int fullness : 2;
> @@ -7221,6 +7235,18 @@ struct zspage {
> unsigned int freeobj;
> };
>
> +struct zspage_5_17 {
> + struct {
> + unsigned int huge : 1;
> + unsigned int fullness : 2;
> + unsigned int class : 9;
> + unsigned int isolated : 3;
> + unsigned int magic : 8;
> + };
> + unsigned int inuse;
> + unsigned int freeobj;
> +};
> +
> /*
> * makedumpfile.c
> */
> diff --git a/diskdump.c b/diskdump.c
> index 2c284ff..d6c114d 100644
> --- a/diskdump.c
> +++ b/diskdump.c
> @@ -2745,6 +2745,8 @@ diskdump_device_dump_info(FILE *ofp)
> }
> }
>
> +struct zram_pageflags zram_pageflags = { 0 };
> +
> static void
> zram_init(void)
> {
> @@ -2754,6 +2756,17 @@ zram_init(void)
> if (INVALID_MEMBER(zram_table_flag))
> MEMBER_OFFSET_INIT(zram_table_flag, "zram_table_entry", "value");
> STRUCT_SIZE_INIT(zram_table_entry, "zram_table_entry");
> + MEMBER_OFFSET_INIT(zspoll_size_class, "zs_pool", "size_class");
> + MEMBER_OFFSET_INIT(size_class_size, "size_class", "size");
> + MEMBER_OFFSET_INIT(zspage_huge, "zspage", "huge");
> +
> + if (!ZRAM_PAGEFLAG_VALUE(ZRAM_LOCK)) {
> + ZRAM_PAGEFLAG_INIT(ZRAM_LOCK, 24);
> + if (!enumerator_value("ZRAM_LOCK", &zram_pageflags.ZRAM_LOCK)
> + && THIS_KERNEL_VERSION >= LINUX(6,1,0))
> + ZRAM_PAGEFLAG_INIT(ZRAM_LOCK, PAGESHIFT() + 1);
> + ZRAM_PAGEFLAG_INIT(ZRAM_SAME, ZRAM_PAGEFLAG_VALUE(ZRAM_LOCK) + 1);
> + }
> }
>
> static unsigned char *
> @@ -2761,9 +2774,11 @@ zram_object_addr(ulong pool, ulong handle, unsigned char *zram_buf)
> {
> ulong obj, off, class, page, zspage;
> struct zspage zspage_s;
> + struct zspage_5_17 zspage_5_17_s;
> physaddr_t paddr;
> unsigned int obj_idx, class_idx, size;
> ulong pages[2], sizes[2];
> + ulong zs_magic;
>
> readmem(handle, KVADDR, &obj, sizeof(void *), "zram entry", FAULT_ON_ERROR);
> obj >>= OBJ_TAG_BITS;
> @@ -2772,11 +2787,19 @@ zram_object_addr(ulong pool, ulong handle, unsigned char *zram_buf)
>
> readmem(page + OFFSET(page_private), KVADDR, &zspage,
> sizeof(void *), "page_private", FAULT_ON_ERROR);
> - readmem(zspage, KVADDR, &zspage_s, sizeof(struct zspage), "zspage", FAULT_ON_ERROR);
>
> - class_idx = zspage_s.class;
> - if (zspage_s.magic != ZSPAGE_MAGIC)
> - error(FATAL, "zspage magic incorrect: %x\n", zspage_s.magic);
> + if (VALID_MEMBER(zspage_huge)) {
> + readmem(zspage, KVADDR, &zspage_5_17_s, sizeof(struct zspage_5_17), "zspage_5_17", FAULT_ON_ERROR);
> + class_idx = zspage_5_17_s.class;
> + zs_magic = zspage_5_17_s.magic;
> + } else {
> + readmem(zspage, KVADDR, &zspage_s, sizeof(struct zspage), "zspage", FAULT_ON_ERROR);
> + class_idx = zspage_s.class;
> + zs_magic = zspage_s.magic;
> + }
> +
> + if (zs_magic != ZSPAGE_MAGIC)
> + error(FATAL, "zspage magic incorrect: %x\n", zs_magic);
>
> class = pool + OFFSET(zspoll_size_class);
> class += (class_idx * sizeof(void *));
> @@ -2794,8 +2817,13 @@ zram_object_addr(ulong pool, ulong handle, unsigned char *zram_buf)
> }
>
> pages[0] = page;
> - readmem(page + OFFSET(page_freelist), KVADDR, &pages[1],
> - sizeof(void *), "page_freelist", FAULT_ON_ERROR);
> + if (VALID_MEMBER(page_freelist)) {
> + readmem(page + OFFSET(page_freelist), KVADDR, &pages[1],
> + sizeof(void *), "page_freelist", FAULT_ON_ERROR);
> + } else {
> + readmem(page + OFFSET(page_index), KVADDR, &pages[1],
> + sizeof(void *), "page_index", FAULT_ON_ERROR);
> + }
> sizes[0] = PAGESIZE() - off;
> sizes[1] = size - sizes[0];
> if (!is_page_ptr(pages[0], &paddr)) {
> @@ -2812,9 +2840,15 @@ zram_object_addr(ulong pool, ulong handle, unsigned char *zram_buf)
> readmem(paddr, PHYSADDR, zram_buf + sizes[0], sizes[1], "zram buffer[1]", FAULT_ON_ERROR);
>
> out:
> - readmem(page, KVADDR, &obj, sizeof(void *), "page flags", FAULT_ON_ERROR);
> - if (!(obj & (1<<10))) { //PG_OwnerPriv1 flag
> - return (zram_buf + ZS_HANDLE_SIZE);
> + if (!VALID_MEMBER(zspage_huge)) {
> + readmem(page, KVADDR, &obj, sizeof(void *), "page flags", FAULT_ON_ERROR);
> + if (!(obj & (1<<10))) { //PG_OwnerPriv1 flag
> + return (zram_buf + ZS_HANDLE_SIZE);
> + }
> + } else {
> + if (!zspage_5_17_s.huge) {
> + return (zram_buf + ZS_HANDLE_SIZE);
> + }
> }
>
> return zram_buf;
> @@ -2929,6 +2963,7 @@ try_zram_decompress(ulonglong pte_val, unsigned char *buf, ulong len, ulonglong
> unsigned char *outbuf = NULL;
> ulong zram, zram_table_entry, sector, index, entry, flags, size,
> outsize, off;
> + unsigned long *same_buf = NULL;
>
> if (INVALID_MEMBER(zram_compressor)) {
> zram_init();
> @@ -2992,11 +3027,18 @@ try_zram_decompress(ulonglong pte_val, unsigned char *buf, ulong len, ulonglong
> sizeof(void *), "entry of table", FAULT_ON_ERROR);
> readmem(zram_table_entry + OFFSET(zram_table_flag), KVADDR, &flags,
> sizeof(void *), "zram_table_flag", FAULT_ON_ERROR);
> - if (!entry || (flags & ZRAM_FLAG_SAME_BIT)) {
> - memset(buf, entry, len);
> +
> + if (!entry || flags & (1 << ZRAM_PAGEFLAG_VALUE(ZRAM_SAME))) {
> + same_buf = (unsigned long *)GETBUF(PAGESIZE());
> + for (int count = 0; count < PAGESIZE() / sizeof(unsigned long); count++) {
> + same_buf[count] = entry;
> + }
> + memcpy(buf, same_buf + off, len);
> + FREEBUF(same_buf);
> goto out;
> }
> - size = flags & (ZRAM_FLAG_SHIFT -1);
> +
> + size = flags & ((1 << ZRAM_PAGEFLAG_VALUE(ZRAM_LOCK)) - 1);
> if (size == 0) {
> len = 0;
> goto out;
> --
> 2.39.0
>
> Thanks.
> Guanyou.
>
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