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@kernel.org

Signed-off-by: chenguanyou <chenguanyou@xiaomi.com>
---
 defs.h     | 13 +++++++++++++
 diskdump.c | 39 ++++++++++++++++++++++++++++++---------
 2 files changed, 43 insertions(+), 9 deletions(-)

diff --git a/defs.h b/defs.h
index 96a7a2a..0af69cc 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 */
@@ -7221,6 +7222,18 @@ struct zspage {
     unsigned int freeobj;
 };

+struct zspage6 {
+    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..99a8112 100644
--- a/diskdump.c
+++ b/diskdump.c
@@ -2761,9 +2761,11 @@ zram_object_addr(ulong pool, ulong handle, unsigned char *zram_buf)
 {
    ulong obj, off, class, page, zspage;
    struct zspage zspage_s;
+   struct zspage6 zspage6_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 +2774,19 @@ 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, &zspage6_s, sizeof(struct zspage6), "zspage6", FAULT_ON_ERROR);
+       class_idx = zspage6_s.class;
+       zs_magic = zspage6_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 +2804,13 @@ 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 +2827,15 @@ 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 (!zspage6_s.huge) {
+           return (zram_buf + ZS_HANDLE_SIZE);
+       }
    }

    return zram_buf;
-- 
2.39.0




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