linux-kernel - Re: [syzbot] [mm?] BUG: Bad page map (7)

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Message-ID: <ZP0xyFnnghM42GcW@casper.infradead.org>
Date:   Sun, 10 Sep 2023 04:02:32 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     syzbot <syzbot+55cc72f8cc3a549119df@...kaller.appspotmail.com>
Cc:     akpm@...ux-foundation.org, fengwei.yin@...el.com,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [mm?] BUG: Bad page map (7)

On Sat, Sep 09, 2023 at 10:12:48AM -0700, syzbot wrote:
> commit 617c28ecab22d98a3809370eb6cb50fa24b7bfe1
> Author: Yin Fengwei <fengwei.yin@...el.com>
> Date:   Wed Aug 2 15:14:05 2023 +0000
> 
>     filemap: batch PTE mappings

Hmm ... I don't know if this is the bug, but ...

#syz test

diff --git a/mm/filemap.c b/mm/filemap.c
index 582f5317ff71..580d0b2b1a7c 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3506,7 +3506,7 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
 		if (count) {
 			set_pte_range(vmf, folio, page, count, addr);
 			folio_ref_add(folio, count);
-			if (in_range(vmf->address, addr, count))
+			if (in_range(vmf->address, addr, count * PAGE_SIZE))
 				ret = VM_FAULT_NOPAGE;
 		}
 
@@ -3520,7 +3520,7 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
 	if (count) {
 		set_pte_range(vmf, folio, page, count, addr);
 		folio_ref_add(folio, count);
-		if (in_range(vmf->address, addr, count))
+		if (in_range(vmf->address, addr, count * PAGE_SIZE))
 			ret = VM_FAULT_NOPAGE;
 	}