The patch titled
Subject: zram: move post-processing target allocation
has been added to the -mm mm-unstable branch. Its filename is
zram-move-post-processing-target-allocation.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zram-move-post-processing-target-allocation.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: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Subject: zram: move post-processing target allocation
Date: Mon, 3 Mar 2025 11:03:20 +0900
Allocate post-processing target in place_pp_slot(). This simplifies
scan_slots_for_writeback() and scan_slots_for_recompress() loops because
we don't need to track pps pointer state anymore. Previously we have to
explicitly NULL the point if it has been added to a post-processing bucket
or re-use previously allocated pointer otherwise and make sure we don't
leak the memory in the end.
We are also fine doing GFP_NOIO allocation, as post-processing can be
called under memory pressure so we better pick as many slots as we can as
soon as we can and start post-processing them, possibly saving the memory.
Allocation failure there is not fatal, we will post-process whatever we
put into the buckets on previous iterations.
Link: https://lkml.kernel.org/r/20250303022425.285971-12-senozhatsky@xxxxxxxxxxxx
Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Cc: Hillf Danton <hdanton@xxxxxxxx>
Cc: Kairui Song <ryncsn@xxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Yosry Ahmed <yosry.ahmed@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 50 ++++++++++++++------------------
1 file changed, 22 insertions(+), 28 deletions(-)
--- a/drivers/block/zram/zram_drv.c~zram-move-post-processing-target-allocation
+++ a/drivers/block/zram/zram_drv.c
@@ -295,15 +295,24 @@ static void release_pp_ctl(struct zram *
kfree(ctl);
}
-static void place_pp_slot(struct zram *zram, struct zram_pp_ctl *ctl,
- struct zram_pp_slot *pps)
+static bool place_pp_slot(struct zram *zram, struct zram_pp_ctl *ctl,
+ u32 index)
{
- u32 idx;
+ struct zram_pp_slot *pps;
+ u32 bid;
+
+ pps = kmalloc(sizeof(*pps), GFP_NOIO | __GFP_NOWARN);
+ if (!pps)
+ return false;
- idx = zram_get_obj_size(zram, pps->index) / PP_BUCKET_SIZE_RANGE;
- list_add(&pps->entry, &ctl->pp_buckets[idx]);
+ INIT_LIST_HEAD(&pps->entry);
+ pps->index = index;
+
+ bid = zram_get_obj_size(zram, pps->index) / PP_BUCKET_SIZE_RANGE;
+ list_add(&pps->entry, &ctl->pp_buckets[bid]);
zram_set_flag(zram, pps->index, ZRAM_PP_SLOT);
+ return true;
}
static struct zram_pp_slot *select_pp_slot(struct zram_pp_ctl *ctl)
@@ -737,15 +746,8 @@ static int scan_slots_for_writeback(stru
unsigned long index,
struct zram_pp_ctl *ctl)
{
- struct zram_pp_slot *pps = NULL;
-
for (; nr_pages != 0; index++, nr_pages--) {
- if (!pps)
- pps = kmalloc(sizeof(*pps), GFP_KERNEL);
- if (!pps)
- return -ENOMEM;
-
- INIT_LIST_HEAD(&pps->entry);
+ bool ok = true;
zram_slot_lock(zram, index);
if (!zram_allocated(zram, index))
@@ -765,14 +767,13 @@ static int scan_slots_for_writeback(stru
!zram_test_flag(zram, index, ZRAM_INCOMPRESSIBLE))
goto next;
- pps->index = index;
- place_pp_slot(zram, ctl, pps);
- pps = NULL;
+ ok = place_pp_slot(zram, ctl, index);
next:
zram_slot_unlock(zram, index);
+ if (!ok)
+ break;
}
- kfree(pps);
return 0;
}
@@ -1827,16 +1828,10 @@ static int scan_slots_for_recompress(str
struct zram_pp_ctl *ctl)
{
unsigned long nr_pages = zram->disksize >> PAGE_SHIFT;
- struct zram_pp_slot *pps = NULL;
unsigned long index;
for (index = 0; index < nr_pages; index++) {
- if (!pps)
- pps = kmalloc(sizeof(*pps), GFP_KERNEL);
- if (!pps)
- return -ENOMEM;
-
- INIT_LIST_HEAD(&pps->entry);
+ bool ok = true;
zram_slot_lock(zram, index);
if (!zram_allocated(zram, index))
@@ -1859,14 +1854,13 @@ static int scan_slots_for_recompress(str
if (zram_get_priority(zram, index) + 1 >= prio_max)
goto next;
- pps->index = index;
- place_pp_slot(zram, ctl, pps);
- pps = NULL;
+ ok = place_pp_slot(zram, ctl, index);
next:
zram_slot_unlock(zram, index);
+ if (!ok)
+ break;
}
- kfree(pps);
return 0;
}
_
Patches currently in -mm which might be from senozhatsky@xxxxxxxxxxxx are
zram-sleepable-entry-locking.patch
zram-permit-preemption-with-active-compression-stream.patch
zram-remove-unused-crypto-include.patch
zram-remove-max_comp_streams-device-attr.patch
zram-remove-second-stage-of-handle-allocation.patch
zram-add-gfp_nowarn-to-incompressible-zsmalloc-handle-allocation.patch
zram-remove-writestall-zram_stats-member.patch
zram-limit-max-recompress-prio-to-num_active_comps.patch
zram-filter-out-recomp-targets-based-on-priority.patch
zram-rework-recompression-loop.patch
zram-move-post-processing-target-allocation.patch
zsmalloc-rename-pool-lock.patch
zsmalloc-sleepable-zspage-reader-lock.patch
zsmalloc-introduce-new-object-mapping-api.patch
zram-switch-to-new-zsmalloc-object-mapping-api.patch
zram-permit-reclaim-in-zstd-custom-allocator.patch
zram-do-not-leak-page-on-recompress_store-error-path.patch
zram-do-not-leak-page-on-writeback_store-error-path.patch
zram-add-might_sleep-to-zcomp-api.patch
