Re: [Resend PATCH 2/6] mm/memcg: remove useless check on page->mem_cgroup
On Thu 13-08-20 17:45:19, Alex Shi wrote: > > > 在 2020/8/13 下午2:20, Michal Hocko 写道: > > On Wed 12-08-20 11:25:53, Alex Shi wrote: > >> >From 999b0fe5fc65865c3b59ff28500d45572a4a9570 Mon Sep 17 00:00:00 2001 > >> From: Alex Shi > >> Date: Wed, 5 Aug 2020 21:02:30 +0800 > >> Subject: [PATCH 2/6] mm/memcg: bail out early from swap accounting when > >> memcg > >> is disabled > >> > >> If we disabled memcg by cgroup_disable=memory, page->memcg will be NULL > >> and so the charge is skipped and that will trigger a warning like below. > >> Let's return from the funcs earlier. > >> > >> ---[ end trace f1f34bfc3b32ed2f ]--- > >> anon flags:0x5005b48008000d(locked|uptodate|dirty|swapbacked) > >> raw: 005005b48008000d dead0100 dead0122 8897c7c76ad1 > >> raw: 0022 0002 > >> page dumped because: VM_WARN_ON_ONCE_PAGE(!memcg) > > > > Yes this is better. It would be even more informative if you added the > > backtrace. > > The stack is a bit long. This doesn't matter. It is informative and potentially useful for future reference. Thanks! -- Michal Hocko SUSE Labs
Re: [Resend PATCH 2/6] mm/memcg: remove useless check on page->mem_cgroup
在 2020/8/13 下午2:20, Michal Hocko 写道: > On Wed 12-08-20 11:25:53, Alex Shi wrote: >> >From 999b0fe5fc65865c3b59ff28500d45572a4a9570 Mon Sep 17 00:00:00 2001 >> From: Alex Shi >> Date: Wed, 5 Aug 2020 21:02:30 +0800 >> Subject: [PATCH 2/6] mm/memcg: bail out early from swap accounting when memcg >> is disabled >> >> If we disabled memcg by cgroup_disable=memory, page->memcg will be NULL >> and so the charge is skipped and that will trigger a warning like below. >> Let's return from the funcs earlier. >> >> ---[ end trace f1f34bfc3b32ed2f ]--- >> anon flags:0x5005b48008000d(locked|uptodate|dirty|swapbacked) >> raw: 005005b48008000d dead0100 dead0122 8897c7c76ad1 >> raw: 0022 0002 >> page dumped because: VM_WARN_ON_ONCE_PAGE(!memcg) > > Yes this is better. It would be even more informative if you added the > backtrace. The stack is a bit long. I still don't know where cause the asm_exc_page_fault? And seems the vma is from kernel not user. >From 999b0fe5fc65865c3b59ff28500d45572a4a9570 Mon Sep 17 00:00:00 2001 From: Alex Shi Date: Wed, 5 Aug 2020 21:02:30 +0800 Subject: [PATCH 2/6] mm/memcg: bail out early from swap accounting when memcg is disabled If we disabled memcg by cgroup_disable=memory, page->memcg will be NULL and so the charge is skipped and that will trigger a warning like below. Let's return from the funcs earlier. anon flags:0x5005b48008000d(locked|uptodate|dirty|swapbacked) raw: 005005b48008000d dead0100 dead0122 8897c7c76ad1 raw: 0022 0002 page dumped because: VM_WARN_ON_ONCE_PAGE(!memcg) ... RIP: 0010:vprintk_emit+0x1f7/0x260 Code: 00 84 d2 74 72 0f b6 15 27 58 64 01 48 c7 c0 00 d4 72 82 84 d2 74 09 f3 90 0f b6 10 84 d2 75 f7 e8 de 0d 00 00 4c 89 e7 57 9d <0f> 1f 44 00 00 e9 62 ff ff ff 80 3d 88 c9 3a 01 00 0f 85 54 fe ff RSP: 0018:c9000faab358 EFLAGS: 0202 RAX: 8272d400 RBX: 005e RCX: 88afd80d0040 RDX: RSI: 0002 RDI: 0202 RBP: c9000faab3a8 R08: 8272d440 R09: 00022480 R10: 00120c77be68bfac R11: 00cd7568 R12: 0202 R13: 0057c0080005 R14: 820a0130 R15: c9000faab3e8 ? vprintk_emit+0x140/0x260 vprintk_default+0x1a/0x20 vprintk_func+0x4f/0xc4 ? vprintk_func+0x4f/0xc4 printk+0x53/0x6a ? xas_load+0xc/0x80 __dump_page.cold.6+0xff/0x4ee ? xas_init_marks+0x23/0x50 ? xas_store+0x30/0x40 ? free_swap_slot+0x43/0xd0 ? put_swap_page+0x119/0x320 ? update_load_avg+0x82/0x580 dump_page+0x9/0xb mem_cgroup_try_charge_swap+0x16e/0x1d0 get_swap_page+0x130/0x210 add_to_swap+0x41/0xc0 shrink_page_list+0x99e/0xdf0 shrink_inactive_list+0x199/0x360 shrink_lruvec+0x40d/0x650 ? _cond_resched+0x14/0x30 ? _cond_resched+0x14/0x30 shrink_node+0x226/0x6e0 do_try_to_free_pages+0xd0/0x400 try_to_free_pages+0xef/0x130 __alloc_pages_slowpath.constprop.127+0x38d/0xbd0 ? ___slab_alloc+0x31d/0x6f0 __alloc_pages_nodemask+0x27f/0x2c0 alloc_pages_vma+0x75/0x220 shmem_alloc_page+0x46/0x90 ? release_pages+0x1ae/0x410 shmem_alloc_and_acct_page+0x77/0x1c0 shmem_getpage_gfp+0x162/0x910 shmem_fault+0x74/0x210 ? filemap_map_pages+0x29c/0x410 __do_fault+0x37/0x190 handle_mm_fault+0x120a/0x1770 exc_page_fault+0x251/0x450 ? asm_exc_page_fault+0x8/0x30 asm_exc_page_fault+0x1e/0x30 Signed-off-by: Alex Shi Reviewed-by: Roman Gushchin Acked-by: Michal Hocko Cc: Johannes Weiner Cc: Michal Hocko Cc: Vladimir Davydov Cc: Andrew Morton Cc: cgro...@vger.kernel.org Cc: linux...@kvack.org Cc: linux-kernel@vger.kernel.org --- mm/memcontrol.c | 6 ++ 1 file changed, 6 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 299382fc55a9..419cf565f40b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -7098,6 +7098,9 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) VM_BUG_ON_PAGE(PageLRU(page), page); VM_BUG_ON_PAGE(page_count(page), page); + if (mem_cgroup_disabled()) + return; + if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) return; @@ -7163,6 +7166,9 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) struct mem_cgroup *memcg; unsigned short oldid; + if (mem_cgroup_disabled()) + return 0; + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) return 0; -- 1.8.3.1
Re: [Resend PATCH 2/6] mm/memcg: remove useless check on page->mem_cgroup
On Wed 12-08-20 11:25:53, Alex Shi wrote: > >From 999b0fe5fc65865c3b59ff28500d45572a4a9570 Mon Sep 17 00:00:00 2001 > From: Alex Shi > Date: Wed, 5 Aug 2020 21:02:30 +0800 > Subject: [PATCH 2/6] mm/memcg: bail out early from swap accounting when memcg > is disabled > > If we disabled memcg by cgroup_disable=memory, page->memcg will be NULL > and so the charge is skipped and that will trigger a warning like below. > Let's return from the funcs earlier. > > ---[ end trace f1f34bfc3b32ed2f ]--- > anon flags:0x5005b48008000d(locked|uptodate|dirty|swapbacked) > raw: 005005b48008000d dead0100 dead0122 8897c7c76ad1 > raw: 0022 0002 > page dumped because: VM_WARN_ON_ONCE_PAGE(!memcg) Yes this is better. It would be even more informative if you added the backtrace. > Signed-off-by: Alex Shi > Reviewed-by: Roman Gushchin > Acked-by: Michal Hocko > Cc: Johannes Weiner > Cc: Michal Hocko > Cc: Vladimir Davydov > Cc: Andrew Morton > Cc: cgro...@vger.kernel.org > Cc: linux...@kvack.org > Cc: linux-kernel@vger.kernel.org > --- > mm/memcontrol.c | 6 ++ > 1 file changed, 6 insertions(+) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 299382fc55a9..419cf565f40b 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -7098,6 +7098,9 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t > entry) > VM_BUG_ON_PAGE(PageLRU(page), page); > VM_BUG_ON_PAGE(page_count(page), page); > > + if (mem_cgroup_disabled()) > + return; > + > if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) > return; > > @@ -7163,6 +7166,9 @@ int mem_cgroup_try_charge_swap(struct page *page, > swp_entry_t entry) > struct mem_cgroup *memcg; > unsigned short oldid; > > + if (mem_cgroup_disabled()) > + return 0; > + > if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) > return 0; > > -- > 1.8.3.1 -- Michal Hocko SUSE Labs
Re: [Resend PATCH 2/6] mm/memcg: remove useless check on page->mem_cgroup
在 2020/8/11 下午9:56, Michal Hocko 写道: > On Tue 11-08-20 20:54:18, Alex Shi wrote: >> >From beeac61119ab39b1869c520c0f272fb8bab93765 Mon Sep 17 00:00:00 2001 >> From: Alex Shi >> Date: Wed, 5 Aug 2020 21:02:30 +0800 >> Subject: [PATCH 2/6] memcg: bail out early from swap accounting when memcg is >> disabled>> >> If we disabled memcg by cgroup_disable=memory, the swap charges are >> still called. Let's return from the funcs earlier. > They are not, are they? page->memcg will be NULL and so the charge is > skipped and that will trigger a warning with your current ordering. Hi Michal, Thanks for comment! Looks like we both agree the memcg wasn't charged, but funcs just are called. :) > > Let me repeat again. Either you put it first in the series and argue > that we can bail out early or keep the ordering then this makes sure the > warning doesn't trigger. > Is the following commit log fine? Thanks! Alex >From 999b0fe5fc65865c3b59ff28500d45572a4a9570 Mon Sep 17 00:00:00 2001 From: Alex Shi Date: Wed, 5 Aug 2020 21:02:30 +0800 Subject: [PATCH 2/6] mm/memcg: bail out early from swap accounting when memcg is disabled If we disabled memcg by cgroup_disable=memory, page->memcg will be NULL and so the charge is skipped and that will trigger a warning like below. Let's return from the funcs earlier. ---[ end trace f1f34bfc3b32ed2f ]--- anon flags:0x5005b48008000d(locked|uptodate|dirty|swapbacked) raw: 005005b48008000d dead0100 dead0122 8897c7c76ad1 raw: 0022 0002 page dumped because: VM_WARN_ON_ONCE_PAGE(!memcg) Signed-off-by: Alex Shi Reviewed-by: Roman Gushchin Acked-by: Michal Hocko Cc: Johannes Weiner Cc: Michal Hocko Cc: Vladimir Davydov Cc: Andrew Morton Cc: cgro...@vger.kernel.org Cc: linux...@kvack.org Cc: linux-kernel@vger.kernel.org --- mm/memcontrol.c | 6 ++ 1 file changed, 6 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 299382fc55a9..419cf565f40b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -7098,6 +7098,9 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) VM_BUG_ON_PAGE(PageLRU(page), page); VM_BUG_ON_PAGE(page_count(page), page); + if (mem_cgroup_disabled()) + return; + if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) return; @@ -7163,6 +7166,9 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) struct mem_cgroup *memcg; unsigned short oldid; + if (mem_cgroup_disabled()) + return 0; + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) return 0; -- 1.8.3.1
Re: [Resend PATCH 2/6] mm/memcg: remove useless check on page->mem_cgroup
On Tue 11-08-20 20:54:18, Alex Shi wrote: > >From beeac61119ab39b1869c520c0f272fb8bab93765 Mon Sep 17 00:00:00 2001 > From: Alex Shi > Date: Wed, 5 Aug 2020 21:02:30 +0800 > Subject: [PATCH 2/6] memcg: bail out early from swap accounting when memcg is > disabled > > If we disabled memcg by cgroup_disable=memory, the swap charges are > still called. Let's return from the funcs earlier. They are not, are they? page->memcg will be NULL and so the charge is skipped and that will trigger a warning with your current ordering. Let me repeat again. Either you put it first in the series and argue that we can bail out early or keep the ordering then this makes sure the warning doesn't trigger. > Signed-off-by: Alex Shi > Reviewed-by: Roman Gushchin > Acked-by: Michal Hocko > Cc: Johannes Weiner > Cc: Michal Hocko > Cc: Vladimir Davydov > Cc: Andrew Morton > Cc: cgro...@vger.kernel.org > Cc: linux...@kvack.org > Cc: linux-kernel@vger.kernel.org > --- > mm/memcontrol.c | 6 ++ > 1 file changed, 6 insertions(+) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 299382fc55a9..419cf565f40b 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -7098,6 +7098,9 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t > entry) > VM_BUG_ON_PAGE(PageLRU(page), page); > VM_BUG_ON_PAGE(page_count(page), page); > > + if (mem_cgroup_disabled()) > + return; > + > if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) > return; > > @@ -7163,6 +7166,9 @@ int mem_cgroup_try_charge_swap(struct page *page, > swp_entry_t entry) > struct mem_cgroup *memcg; > unsigned short oldid; > > + if (mem_cgroup_disabled()) > + return 0; > + > if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) > return 0; > > -- > 1.8.3.1 -- Michal Hocko SUSE Labs
Re: [Resend PATCH 2/6] mm/memcg: remove useless check on page->mem_cgroup
>From beeac61119ab39b1869c520c0f272fb8bab93765 Mon Sep 17 00:00:00 2001 From: Alex Shi Date: Wed, 5 Aug 2020 21:02:30 +0800 Subject: [PATCH 2/6] memcg: bail out early from swap accounting when memcg is disabled If we disabled memcg by cgroup_disable=memory, the swap charges are still called. Let's return from the funcs earlier. Signed-off-by: Alex Shi Reviewed-by: Roman Gushchin Acked-by: Michal Hocko Cc: Johannes Weiner Cc: Michal Hocko Cc: Vladimir Davydov Cc: Andrew Morton Cc: cgro...@vger.kernel.org Cc: linux...@kvack.org Cc: linux-kernel@vger.kernel.org --- mm/memcontrol.c | 6 ++ 1 file changed, 6 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 299382fc55a9..419cf565f40b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -7098,6 +7098,9 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) VM_BUG_ON_PAGE(PageLRU(page), page); VM_BUG_ON_PAGE(page_count(page), page); + if (mem_cgroup_disabled()) + return; + if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) return; @@ -7163,6 +7166,9 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) struct mem_cgroup *memcg; unsigned short oldid; + if (mem_cgroup_disabled()) + return 0; + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) return 0; -- 1.8.3.1
Re: [Resend PATCH 2/6] mm/memcg: remove useless check on page->mem_cgroup
在 2020/8/11 下午7:30, Michal Hocko 写道: > subject line looks like a left over. It doesn't match the path. Did you > mean > memcg: bail out early from swap accounting when memcg is disabled? It's much better, Thanks for correction! > > Btw. if this patch was first in the series then you wouldn't need to > mention the warnings that would trigger based on your previous patch. > I am fine with both ways but mentioning the warning is usefule. Right. but the patch is very simple, w/o warning message doesn't cuase trouble. So, removing the 'and keep WARN_ON monitor' make sense too. Do I need a resend for the commit log change? Thanks a lot! Alex > > On Tue 11-08-20 19:10:28, Alex Shi wrote: >> If we disabled memcg by cgroup_disable=memory, the swap charges are >> still called. Let's return from the funcs earlier and keep WARN_ON >> monitor. >> >> Signed-off-by: Alex Shi >> Reviewed-by: Roman Gushchin >> Acked-by: Michal Hocko >> Cc: Johannes Weiner >> Cc: Michal Hocko >> Cc: Vladimir Davydov >> Cc: Andrew Morton >> Cc: cgro...@vger.kernel.org >> Cc: linux...@kvack.org >> Cc: linux-kernel@vger.kernel.org >> --- >> mm/memcontrol.c | 6 ++ >> 1 file changed, 6 insertions(+) >> >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >> index 299382fc55a9..419cf565f40b 100644 >> --- a/mm/memcontrol.c >> +++ b/mm/memcontrol.c >> @@ -7098,6 +7098,9 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t >> entry) >> VM_BUG_ON_PAGE(PageLRU(page), page); >> VM_BUG_ON_PAGE(page_count(page), page); >> >> +if (mem_cgroup_disabled()) >> +return; >> + >> if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) >> return; >> >> @@ -7163,6 +7166,9 @@ int mem_cgroup_try_charge_swap(struct page *page, >> swp_entry_t entry) >> struct mem_cgroup *memcg; >> unsigned short oldid; >> >> +if (mem_cgroup_disabled()) >> +return 0; >> + >> if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) >> return 0; >> >> -- >> 1.8.3.1 >
Re: [Resend PATCH 2/6] mm/memcg: remove useless check on page->mem_cgroup
subject line looks like a left over. It doesn't match the path. Did you mean memcg: bail out early from swap accounting when memcg is disabled? Btw. if this patch was first in the series then you wouldn't need to mention the warnings that would trigger based on your previous patch. I am fine with both ways but mentioning the warning is usefule. On Tue 11-08-20 19:10:28, Alex Shi wrote: > If we disabled memcg by cgroup_disable=memory, the swap charges are > still called. Let's return from the funcs earlier and keep WARN_ON > monitor. > > Signed-off-by: Alex Shi > Reviewed-by: Roman Gushchin > Acked-by: Michal Hocko > Cc: Johannes Weiner > Cc: Michal Hocko > Cc: Vladimir Davydov > Cc: Andrew Morton > Cc: cgro...@vger.kernel.org > Cc: linux...@kvack.org > Cc: linux-kernel@vger.kernel.org > --- > mm/memcontrol.c | 6 ++ > 1 file changed, 6 insertions(+) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 299382fc55a9..419cf565f40b 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -7098,6 +7098,9 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t > entry) > VM_BUG_ON_PAGE(PageLRU(page), page); > VM_BUG_ON_PAGE(page_count(page), page); > > + if (mem_cgroup_disabled()) > + return; > + > if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) > return; > > @@ -7163,6 +7166,9 @@ int mem_cgroup_try_charge_swap(struct page *page, > swp_entry_t entry) > struct mem_cgroup *memcg; > unsigned short oldid; > > + if (mem_cgroup_disabled()) > + return 0; > + > if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) > return 0; > > -- > 1.8.3.1 -- Michal Hocko SUSE Labs
[Resend PATCH 2/6] mm/memcg: remove useless check on page->mem_cgroup
If we disabled memcg by cgroup_disable=memory, the swap charges are still called. Let's return from the funcs earlier and keep WARN_ON monitor. Signed-off-by: Alex Shi Reviewed-by: Roman Gushchin Acked-by: Michal Hocko Cc: Johannes Weiner Cc: Michal Hocko Cc: Vladimir Davydov Cc: Andrew Morton Cc: cgro...@vger.kernel.org Cc: linux...@kvack.org Cc: linux-kernel@vger.kernel.org --- mm/memcontrol.c | 6 ++ 1 file changed, 6 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 299382fc55a9..419cf565f40b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -7098,6 +7098,9 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) VM_BUG_ON_PAGE(PageLRU(page), page); VM_BUG_ON_PAGE(page_count(page), page); + if (mem_cgroup_disabled()) + return; + if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) return; @@ -7163,6 +7166,9 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) struct mem_cgroup *memcg; unsigned short oldid; + if (mem_cgroup_disabled()) + return 0; + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) return 0; -- 1.8.3.1
