The patch titled
Subject: mm/vmalloc: skip the uninitilized vmalloc areas
has been added to the -mm mm-unstable branch. Its filename is
mm-vmalloc-skip-the-uninitilized-vmalloc-areas.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vmalloc-skip-the-uninitilized-vmalloc-areas.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Baoquan He <bhe@xxxxxxxxxx>
Subject: mm/vmalloc: skip the uninitilized vmalloc areas
Date: Mon, 6 Feb 2023 16:40:18 +0800
For areas allocated via vmalloc_xxx() APIs, it searches for unmapped area
to reserve and allocates new pages to map into, please see function
__vmalloc_node_range(). During the process, flag VM_UNINITIALIZED is set
in vm->flags to indicate that the pages allocation and mapping haven't
been done, until clear_vm_uninitialized_flag() is called to clear
VM_UNINITIALIZED.
For this kind of area, if VM_UNINITIALIZED is still set, let's ignore it
in vread() because pages newly allocated and being mapped in that area
only contains zero data. reading them out by aligned_vread() is wasting
time.
Link: https://lkml.kernel.org/r/20230206084020.174506-6-bhe@xxxxxxxxxx
Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
Reviewed-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
Cc: Dan Carpenter <error27@xxxxxxxxx>
Cc: Stephen Brennan <stephen.s.brennan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/vmalloc.c~mm-vmalloc-skip-the-uninitilized-vmalloc-areas
+++ a/mm/vmalloc.c
@@ -3587,6 +3587,11 @@ long vread(char *buf, char *addr, unsign
if (!vm && !flags)
continue;
+ if (vm && (vm->flags & VM_UNINITIALIZED))
+ continue;
+ /* Pair with smp_wmb() in clear_vm_uninitialized_flag() */
+ smp_rmb();
+
vaddr = (char *) va->va_start;
size = vm ? get_vm_area_size(vm) : va_size(va);
_
Patches currently in -mm which might be from bhe@xxxxxxxxxx are
mm-vmallocc-add-used_map-into-vmap_block-to-track-space-of-vmap_block.patch
mm-vmallocc-add-flags-to-mark-vm_map_ram-area.patch
mm-vmallocc-allow-vread-to-read-out-vm_map_ram-areas.patch
mm-vmalloc-explicitly-identify-vm_map_ram-area-when-shown-in-proc-vmcoreinfo.patch
mm-vmalloc-skip-the-uninitilized-vmalloc-areas.patch
powerpc-mm-add-vm_ioremap-flag-to-the-vmalloc-area.patch
sh-mm-set-vm_ioremap-flag-to-the-vmalloc-area.patch
