+ mm-gup-fix-gup_pud_range-for-dax.patch added to mm-hotfixes-unstable branch - Linux-stable-mirror

7 Dec 2022

The patch titled
     Subject: mm/gup: fix gup_pud_range() for dax
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-gup-fix-gup_pud_range-for-dax.patch
This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...
This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Saurabh Sengar ssengar@linux.microsoft.com
Subject: mm/gup: fix gup_pud_range() for dax
Date: Tue, 6 Dec 2022 22:00:53 -0800
For dax pud, pud_huge() returns true on x86. So the function works as long
as hugetlb is configured. However, dax doesn't depend on hugetlb.
Commit 414fd080d125 ("mm/gup: fix gup_pmd_range() for dax") fixed
devmap-backed huge PMDs, but missed devmap-backed huge PUDs. Fix this as
well.
This fixes the below kernel panic:
general protection fault, probably for non-canonical address 0x69e7c000cc478: 0000 [#1] SMP
    < snip >
Call Trace:
<TASK>
get_user_pages_fast+0x1f/0x40
iov_iter_get_pages+0xc6/0x3b0
? mempool_alloc+0x5d/0x170
bio_iov_iter_get_pages+0x82/0x4e0
? bvec_alloc+0x91/0xc0
? bio_alloc_bioset+0x19a/0x2a0
blkdev_direct_IO+0x282/0x480
? __io_complete_rw_common+0xc0/0xc0
? filemap_range_has_page+0x82/0xc0
generic_file_direct_write+0x9d/0x1a0
? inode_update_time+0x24/0x30
__generic_file_write_iter+0xbd/0x1e0
blkdev_write_iter+0xb4/0x150
? io_import_iovec+0x8d/0x340
io_write+0xf9/0x300
io_issue_sqe+0x3c3/0x1d30
? sysvec_reschedule_ipi+0x6c/0x80
__io_queue_sqe+0x33/0x240
? fget+0x76/0xa0
io_submit_sqes+0xe6a/0x18d0
? __fget_light+0xd1/0x100
__x64_sys_io_uring_enter+0x199/0x880
? __context_tracking_enter+0x1f/0x70
? irqentry_exit_to_user_mode+0x24/0x30
? irqentry_exit+0x1d/0x30
? __context_tracking_exit+0xe/0x70
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fc97c11a7be
    < snip >
</TASK>
---[ end trace 48b2e0e67debcaeb ]---
RIP: 0010:internal_get_user_pages_fast+0x340/0x990
    < snip >
Kernel panic - not syncing: Fatal exception
Kernel Offset: disabled
Link: https://lkml.kernel.org/r/1670392853-28252-1-git-send-email-ssengar@linux.mi...
Fixes: 414fd080d125 ("mm/gup: fix gup_pmd_range() for dax")
Signed-off-by: John Starks jostarks@microsoft.com
Signed-off-by: Saurabh Sengar ssengar@linux.microsoft.com
Cc: Jan Kara jack@suse.cz
Cc: Yu Zhao yuzhao@google.com
Cc: Jason Gunthorpe jgg@nvidia.com
Cc: John Hubbard jhubbard@nvidia.com
Cc: David Hildenbrand david@redhat.com
Cc: Dan Williams dan.j.williams@intel.com
Cc: Alistair Popple apopple@nvidia.com
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Morton akpm@linux-foundation.org
---

--- a/mm/gup.c~mm-gup-fix-gup_pud_range-for-dax
+++ a/mm/gup.c
@@ -2852,7 +2852,7 @@ static int gup_pud_range(p4d_t *p4dp, p4
    	next = pud_addr_end(addr, end);
    	if (unlikely(!pud_present(pud)))
    		return 0;
-		if (unlikely(pud_huge(pud))) {
+		if (unlikely(pud_huge(pud) || pud_devmap(pud))) {
    		if (!gup_huge_pud(pud, pudp, addr, next, flags,
    				  pages, nr))
    			return 0;
_
Patches currently in -mm which might be from ssengar@linux.microsoft.com are
mm-gup-fix-gup_pud_range-for-dax.patch

    