[PATCH] Fix: move huge compressed obj from page to zspage

[陈冠有 <chenguanyou@xxxxxxxxxx>]

when zspage define 'huge', crash-utility zram decompress fail.

we need to be compatible with the previous kernel,

so we can't define 'huge' directly in zspage, just move to the right when calculating.

Link: https://lkml.kernel.org/r/20211115185909.3949505-6-minchan@xxxxxxxxxx

Signed-off-by: chenguanyou <chenguanyou@xxxxxxxxxx>

---

 defs.h     |  4 ++++

 diskdump.c | 21 ++++++++++++++++-----

 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/defs.h b/defs.h

index 96a7a2a..ac19410 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 */

@@ -7212,6 +7213,9 @@ ulong try_zram_decompress(ulonglong pte_val, unsigned char *buf, ulong len, ulon

 #define ZRAM_FLAG_SAME_BIT      (1<<25)

 struct zspage {

     struct {

+        // Link: https://lkml.kernel.org/r/20211115185909.3949505-6-minchan@xxxxxxxxxx

+        // unsigned int huge : 1;  // compatible

+

         unsigned int fullness : 2;

         unsigned int class : 9;

         unsigned int isolated : 3;

diff --git a/diskdump.c b/diskdump.c

index 2c284ff..891ee2f 100644

--- a/diskdump.c

+++ b/diskdump.c

@@ -2764,6 +2764,8 @@ zram_object_addr(ulong pool, ulong handle, unsigned char *zram_buf)

    physaddr_t paddr;

    unsigned int obj_idx, class_idx, size;

    ulong pages[2], sizes[2];

+   ulong zspage_shift = 0;

+   ulong zs_magic;

    readmem(handle, KVADDR, &obj, sizeof(void *), "zram entry", FAULT_ON_ERROR);

    obj >>= OBJ_TAG_BITS;

@@ -2774,9 +2776,13 @@ zram_object_addr(ulong pool, ulong handle, unsigned char *zram_buf)

            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))

+       zspage_shift = 1; // huge shift

+

+   class_idx = zspage_s.class >> zspage_shift;

+   zs_magic = zspage_s.magic >> zspage_shift;

+   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 +2800,13 @@ 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)) {

-- 

2.39.0

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