the exiting makedumpfile is almost there... :)

[Ken'ichi Ohmichi]

Hi Dave, Jay,

Dave Anderson wrote:
> We just ran into a similar problem using an older version of makedumpfile,
> but looking at the latest makedumpfile code, it's seems that you could
> run into the same problem.
> 
> In exclude_unnecessary_pages(), if a physical page is in a memory
> hole, then it skips the page and continues.  In our case, that happened,
> but when it started up again, the next legitimate pfn was well beyond
> the previously-read cache of 512 pages.  But since the new legit page
> wasn't modulo-512, it didn't refresh the page cache, and it ended up
> using stale page data (page->flags) and ended up excluding legitimate
> pages:
> 
>                 for (; pfn < mmd->pfn_end;
>                     pfn++, mem_map += SIZE(page),
>                     paddr += info->page_size) {
> 
>                         /*
>                          * Exclude the memory hole.
>                          */
>                         if (!is_in_segs(paddr))
>                                 continue;
> 
>                         if ((pfn % PGMM_CACHED) == 0) {
>                                 if (pfn + PGMM_CACHED < mmd->pfn_end)
>                                         pfn_mm = PGMM_CACHED;
>                                 else
>                                         pfn_mm = mmd->pfn_end - pfn;
>                                 if (!readmem(VADDR, mem_map, page_cache,
>                                     SIZE(page) * pfn_mm))
>                                         goto out;
>                         }
> 
> We fixed it by doing something like this:
> 
>          if (!is_in_segs(paddr)) {
>                  reset_cache = 1;
>                  continue;
>          }
> 
>          if (((pfn % PGMM_CACHED) == 0) || reset_cache) {
>                  reset_cache = 0;
>                  ...

Great, you are right.
Thank you for fixing it  :-) 

Jay, could you try Dave's fixing like the attached patch ?


Thanks
Ken'ichi Ohmichi

---
diff -puN backup/makedumpfile-1.2.9/makedumpfile.c makedumpfile/makedumpfile.c
--- backup/makedumpfile-1.2.9/makedumpfile.c	2008-09-04 16:31:58.000000000 +0900
+++ makedumpfile/makedumpfile.c	2008-09-24 10:04:53.000000000 +0900
@@ -4130,6 +4130,7 @@ exclude_zero_pages(void)
 int
 exclude_unnecessary_pages(void)
 {
+	int reset_cache;
 	unsigned int mm;
 	unsigned long mem_map;
 	unsigned long long pfn, paddr, pfn_mm;
@@ -4156,6 +4157,8 @@ exclude_unnecessary_pages(void)
 		if (mem_map == NOT_MEMMAP_ADDR)
 			continue;
 
+		reset_cache = 1;
+
 		for (; pfn < mmd->pfn_end;
 		    pfn++, mem_map += SIZE(page),
 		    paddr += info->page_size) {
@@ -4163,10 +4166,11 @@ exclude_unnecessary_pages(void)
 			/*
 			 * Exclude the memory hole.
 			 */
-			if (!is_in_segs(paddr))
+			if (!is_in_segs(paddr)) {
+				reset_cache = 1;
 				continue;
-
-			if ((pfn % PGMM_CACHED) == 0) {
+			}
+			if (((pfn % PGMM_CACHED) == 0) || reset_cache) {
 				if (pfn + PGMM_CACHED < mmd->pfn_end)
 					pfn_mm = PGMM_CACHED;
 				else
@@ -4174,6 +4178,7 @@ exclude_unnecessary_pages(void)
 				if (!readmem(VADDR, mem_map, page_cache,
 				    SIZE(page) * pfn_mm))
 					goto out;
+				reset_cache = 0;
 			}
 			pcache  = page_cache + ((pfn%PGMM_CACHED) * SIZE(page));
 			flags   = ULONG(pcache + OFFSET(page.flags));