The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.19.y git checkout FETCH_HEAD git cherry-pick -x c567f2948f57bdc03ed03403ae0234085f376b7d # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024040123-denial-syndrome-2d01@gregkh' --subject-prefix 'PATCH 4.19.y' HEAD^..

Possible dependencies:

c567f2948f57 ("Revert "x86/mm/ident_map: Use gbpages only where full GB page should be mapped."") 0a845e0f6348 ("mm/treewide: replace pud_large() with pud_leaf()") d794734c9bbf ("x86/mm/ident_map: Use gbpages only where full GB page should be mapped.") 27af67f35631 ("powerpc/book3s64/mm: enable transparent pud hugepage") 104c49d5b6dc ("powerpc/mm/trace: convert trace event to trace event class") 040ec6202bb8 ("powerpc/mm/book3s64: Use pmdp_ptep helper instead of typecasting.") bb1520d581a3 ("s390/mm: start kernel with DAT enabled") 9c3205b2b062 ("s390/boot: cleanup decompressor header files") 47477c84b891 ("Merge tag 's390-6.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From c567f2948f57bdc03ed03403ae0234085f376b7d Mon Sep 17 00:00:00 2001 From: Ingo Molnar mingo@kernel.org Date: Mon, 25 Mar 2024 11:47:51 +0100 Subject: [PATCH] Revert "x86/mm/ident_map: Use gbpages only where full GB page should be mapped."

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...

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: 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... Fixes: d794734c9bbf ("x86/mm/ident_map: Use gbpages only where full GB page should be mapped.")

diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c index a204a332c71f..968d7005f4a7 100644 --- a/arch/x86/mm/ident_map.c +++ b/arch/x86/mm/ident_map.c @@ -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;