That was quick.
Thanks Dave!
On Fri, Dec 2, 2016 at 10:59 AM, Dave Anderson <anderson@xxxxxxxxxx> wrote:
----- Original Message -----
> In this mode, the freelist can be an object and if the slab is full,
> there is no freelist. On the next free, an object is recycled to be used
> as the freelist but not clean-up. This change will go through only
> known freed objects to prevent errors of wrong/corrupt freelist entries.
>
> Related to the linux kernel commit: b03a017bebc403d40aa53a092e79b3020786537d. Thanks Thomas -- the patch queued for crash-7.1.8:
https://github.com/crash-utility/crash/commit/ 59fbaf3e4b030b150f750f5b0ac7df c3eafaa78f
Dave
> --
> ---
> memory.c | 30 ++++++++++++++++++++++++------
> 1 file changed, 24 insertions(+), 6 deletions(-)
>
> diff --git a/memory.c b/memory.c
> index 4eac413..774d090 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -9880,6 +9880,7 @@ ignore_cache(struct meminfo *si, char *name)
> #define SLAB_MAGIC_DESTROYED 0xB2F23C5AUL /* slab has been destroyed
> */
>
> #define SLAB_CFLGS_BUFCTL 0x020000UL /* bufctls in own cache */
> +#define SLAB_CFLGS_OBJFREELIST 0x40000000UL /* Freelist as an object */
>
> #define KMEM_SLAB_ADDR (1)
> #define KMEM_BUFCTL_ADDR (2)
> @@ -12439,11 +12440,13 @@ gather_slab_free_list_percpu(struct meminfo *si)
> static void
> gather_slab_free_list_slab_overload_page(struct meminfo *si)
> {
> - int i, active;
> + int i, active, start_offset;
> ulong obj, objnr, cnt, freelist;
> unsigned char *ucharptr;
> unsigned short *ushortptr;
> unsigned int *uintptr;
> + unsigned int cache_flags, overload_active;
> + ulong slab_overload_page;
>
> if (CRASHDEBUG(1))
> fprintf(fp, "slab page: %lx active: %ld si->c_num: %ld\n",
> @@ -12452,12 +12455,19 @@ gather_slab_free_list_slab_overload_page(struct
> meminfo *si)
> if (si->s_inuse == si->c_num )
> return;
>
> - readmem(si->slab - OFFSET(page_lru) + OFFSET(page_freelist),
> + slab_overload_page = si->slab - OFFSET(page_lru);
> + readmem(slab_overload_page + OFFSET(page_freelist),
> KVADDR, &freelist, sizeof(void *), "page freelist",
> FAULT_ON_ERROR);
> readmem(freelist, KVADDR, si->freelist,
> si->freelist_index_size * si->c_num,
> "freelist array", FAULT_ON_ERROR);
> + readmem(si->cache+OFFSET(kmem_cache_s_flags),
> + KVADDR, &cache_flags, sizeof(uint),
> + "kmem_cache_s flags", FAULT_ON_ERROR);
> + readmem(slab_overload_page + OFFSET(page_active),
> + KVADDR, &overload_active, sizeof(uint),
> + "active", FAULT_ON_ERROR);
>
> BNEG(si->addrlist, sizeof(ulong) * (si->c_num+1));
> cnt = objnr = 0;
> @@ -12466,14 +12476,22 @@ gather_slab_free_list_slab_overload_page(struct
> meminfo *si)
> uintptr = NULL;
> active = si->s_inuse;
>
> + /*
> + * On an OBJFREELIST slab, the object might have been recycled
> + * and everything before the active count can be random data.
> + */
> + start_offset = 0;
> + if (cache_flags & SLAB_CFLGS_OBJFREELIST)
> + start_offset = overload_active;
> +
> switch (si->freelist_index_size)
> {
> - case 1: ucharptr = (unsigned char *)si->freelist; break;
> - case 2: ushortptr = (unsigned short *)si->freelist; break;
> - case 4: uintptr = (unsigned int *)si->freelist; break;
> + case 1: ucharptr = (unsigned char *)si->freelist + start_offset; break;
> + case 2: ushortptr = (unsigned short *)si->freelist + start_offset; break;
> + case 4: uintptr = (unsigned int *)si->freelist + start_offset; break;
> }
>
> - for (i = 0; i < si->c_num; i++) {
> + for (i = start_offset; i < si->c_num; i++) {
> switch (si->freelist_index_size)
> {
> case 1: objnr = (ulong)*ucharptr++; break;
> --
> 2.8.0.rc3.226.g39d4020
>
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>
Thomas
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