linux-kernel - Re: [PATCH v2 3/3] arm: extend pfn_valid to take into accound freed memory map alignment

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Message-ID: <YNqwl8EPVYZJV0EF@linux.ibm.com>
Date:   Tue, 29 Jun 2021 08:33:11 +0300
From:   Mike Rapoport <rppt@...ux.ibm.com>
To:     Tony Lindgren <tony@...mide.com>
Cc:     Mike Rapoport <rppt@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Russell King <linux@...linux.org.uk>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-omap@...r.kernel.org, regressions@...ts.linux.dev
Subject: Re: [PATCH v2 3/3] arm: extend pfn_valid to take into accound freed
 memory map alignment

On Mon, Jun 28, 2021 at 06:26:26PM +0300, Tony Lindgren wrote:
> * Mike Rapoport <rppt@...ux.ibm.com> [210628 14:07]:
> > Can you please send log with 'memblock=debug' added to the command line?
> 
> Sure, log now available at:
> 
> http://muru.com/beagle-x15.txt

Hmm, no clues yet :(

Do you have CONFIG_DEBUG_VM, CONFIG_DEBUG_VM_PGFLAGS and
CONFIG_PAGE_POISONING enabled in your config?
If not, can you please enable them and see if any of VM_BUG_* triggers?

Do you use FLATMEM or SPARSEMEM in your config?

Let's try seeing what PFNs get false results from pfn_valid, maybe this
will give a better lead.

diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 6162a070a410..66985fc3e730 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -126,10 +126,16 @@ int pfn_valid(unsigned long pfn)
 {
 	phys_addr_t addr = __pfn_to_phys(pfn);
 	unsigned long pageblock_size = PAGE_SIZE * pageblock_nr_pages;
+	bool overlaps = memblock_overlaps_region(&memblock.memory,
+				     ALIGN_DOWN(addr, pageblock_size),
+				     pageblock_size);
 
 	if (__phys_to_pfn(addr) != pfn)
 		return 0;
 
+	if (memblock_is_map_memory(addr) != overlaps)
+		pr_info("%s(%pS): pfn: %lx: is_map: %d overlaps: %d\n", __func__, (void *)_RET_IP_, pfn, memblock_is_map_memory(addr), overlaps);
+
 	/*
 	 * If address less than pageblock_size bytes away from a present
 	 * memory chunk there still will be a memory map entry for it

-- 
Sincerely yours,
Mike.