On Mon, Nov 30, 2020 at 6:24 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > > On Mon, Nov 30, 2020 at 05:20:25PM -0800, Dan Williams wrote: > > Kirill, Willy, compound page experts, > > > > I am seeking some debug ideas about the following splat: > > > > BUG: Bad page state in process lt-pmem-ns pfn:121a12 > > page:0000000051ef73f7 refcount:0 mapcount:-1024 > > mapping:0000000000000000 index:0x0 pfn:0x121a12 > > Mapcount of -1024 is the signature of: > > #define PG_guard 0x00000400 Oh, thanks for that. I overlooked how mapcount is overloaded. Although in v5.10-rc4 that value is: #define PG_table 0x00000400 > > (the bits are inverted, so this turns into 0xfffffbff which is reported > as -1024) > > I assume you have debug_pagealloc enabled? Added it, but no extra spew. I'll dig a bit more on how PG_table is not being cleared in this case.
