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Revert "x86/mm/ident_map: Use gbpages only where full GB page should be mapped." 

This reverts commit d794734c9b.

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 d794734c9b 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:

  0a845e0f63 mm/treewide: replace pud_large() with pud_leaf()

Signed-off-by: Ingo 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: d794734c9b ("x86/mm/ident_map: Use gbpages only where full GB page should be mapped.")
This commit is contained in:
Ingo Molnar 2024-03-25 11:47:51 +01:00
parent 91491e5fb0
commit c567f2948f
1 changed files with 5 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
arch/x86/mm/ident_map.c
View File

@ -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_leaf(*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;