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Commit b6676294 authored by Ingo Molnar's avatar Ingo Molnar Committed by Greg Kroah-Hartman
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Revert "x86/mm/ident_map: Use gbpages only where full GB page should be mapped." 

commit c567f2948f57bdc03ed03403ae0234085f376b7d upstream.

This reverts commit d794734c9bbfe22f86686dc2909c25f5ffe1a572.

While the original change tries to fix a bug, it also unintentionally broke
existing systems, see the regressions reported at:

  https://lore.kernel.org/all/3a1b9909-45ac-4f97-ad68-d16ef1ce99db@pavinjoseph.com/



Since d794734c9bbf was also marked for -stable, let's back it out before
causing more damage.

Note that due to another upstream change the revert was not 100% automatic:

  0a845e0f6348 mm/treewide: replace pud_large() with pud_leaf()

Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: <stable@vger.kernel.org>
Cc: Russ Anderson <rja@hpe.com>
Cc: Steve Wahl <steve.wahl@hpe.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://lore.kernel.org/all/3a1b9909-45ac-4f97-ad68-d16ef1ce99db@pavinjoseph.com/


Fixes: d794734c9bbf ("x86/mm/ident_map: Use gbpages only where full GB page should be mapped.")
Signed-off-by: default avatarSteve Wahl <steve.wahl@hpe.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d275de8e

arch/x86/mm/ident_map.c

+5 −18
Original line number Diff line number Diff line
@@ -26,31 +26,18 @@ static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page, 
	for (; addr < end; addr = next) {

		pud_t *pud = pud_page + pud_index(addr);

		pmd_t *pmd;

		bool use_gbpage;



		next = (addr & PUD_MASK) + PUD_SIZE;

		if (next > end)

			next = end;



		/* if this is already a gbpage, this portion is already mapped */

		if (pud_large(*pud))

			continue;



		/* Is using a gbpage allowed? */

		use_gbpage = info->direct_gbpages;



		/* Don't use gbpage if it maps more than the requested region. */

		/* at the begining: */

		use_gbpage &= ((addr & ~PUD_MASK) == 0);

		/* ... or at the end: */

		use_gbpage &= ((next & ~PUD_MASK) == 0);



		/* Never overwrite existing mappings */

		use_gbpage &= !pud_present(*pud);



		if (use_gbpage) {

		if (info->direct_gbpages) {

			pud_t pudval;



			if (pud_present(*pud))

				continue;



			addr &= PUD_MASK;

			pudval = __pud((addr - info->offset) | info->page_flag);

			set_pud(pud, pudval);

			continue;